I may have found something in the Log or at least I see some error messages, namely this one in particular:
0035990: Playback: CJRVideoEngine::Open: FFmpeg DLLs are not available.
0035934: 140234557650880: Playback: CPlayerZone::Play: Start
0035934: 140232645514944: Playback: CPlayerZoneDisplayInfoLoadImageThread::Thread: Start
0035934: 140232645514944: Playback: CPlayerZoneDisplayInfoLoadImageThread::Thread: Image: 0000000000000000
0035934: 140232645514944: Playback: CPlayerZoneDisplayInfoLoadImageThread::Thread: Finish (0 ms)
0035934: 140234557650880: Playback: CPlayerZoneDisplayInfoUpdateThread::Destructor: Start
0035934: 140232263526080: Playback: CPlayerZoneDisplayInfoUpdateThread::Thread: Finish (599138 ms)
0035954: 140234557650880: Playback: CPlayerZoneDisplayInfoUpdateThread::Destructor: Finish (20 ms)
0035957: 140234557650880: Playback: CPlayerZone::Play: Handling exclusive playback zones
0035957: 140234557650880: Playback: CPlayerZone::Play: Getting actual playback track
0035958: 140234557650880: Playback: CPlayerZone::Play: Processing play for '/mnt/Movies/Ficção científica/Venom - Let There Be Carnage (2021)/Venom - Let There Be Carnage (2021).mkv'
0035958: 140234557650880: Playback: CPlayerZone::Play: Updating internal track info
0035959: 140234557650880: Playback: CPlayerZone::Play: Playing: <XMLFN version="1.0"><Item Name="Filename">/mnt/Movies/Ficção científica/Venom - Let There Be Carnage (2021)/Venom - Let There Be Carnage (2021).mkv</Item><Item Name="FPS">23.9760208129882812</Item><Item Name="PlaylistIndex">0</Item><Item Name="AlbumSequentialWithLastTrack">0</Item><Item Name="HDR">DolbyVision Profile 8.1, HDR10-compatible</Item><Item Name="AspectRatio">1.78</Item><Item Name="DurationSeconds">5836</Item><Item Name="CenterFocusMixing">1</Item><Item Name="VolumeReset">1</Item><Item Name="ErrorFreeMode">0</Item><Item Name="VolumePeakLevels"></Item><Item Name="MediaType">Video</Item><Item Name="DatabaseKey">2570623</Item><Item Name="CompressionInfo">mkv video (video: hevc, audio: truehd)</Item><Item Name="VolumeTrackMaxSafeGain">-1</Item><Item Name="Bitrate">78075</Item><Item Name="Bookmark"></Item><Item Name="PlaybackInfo"></Item><Item Name="BlackBarCrop"></Item><Item Name="DRMProtected"></Item><Item Name="VolumeLeveling">0</Item><Item Name="DSP"></Item><Item Name="FileType">mkv</Item><Item Name="UserInterfaceModeChangeEventHandle">0000000000000000</Item></XMLFN>
0035959: 140234557650880: Playback: CJRPlaybackEngine::Play: Start
0035959: 140234557650880: Playback: CJRPlaybackEngine::StopInternal: Start
0035959: 140234557650880: Playback: CJRPlaybackEngine::StopInternal: Finish (0 ms)
0035959: 140234557650880: Playback: CJRPlaybackEngine::Play: Volume protection: 0
0035959: 140234557650880: Playback: CJRPlaybackEngine::Play: Playing: /mnt/Movies/Ficção científica/Venom - Let There Be Carnage (2021)/Venom - Let There Be Carnage (2021).mkv
0035959: 140234557650880: Playback: CJRPlaybackEngine::Play: Filetype: mkv; Type: 18; Can play: 1; Playback object: 0x55fab63f57f0
0035959: 140234557650880: Playback: CJRPlaybackEngine::StartPlayFile: Start
0035959: 140234557650880: Playback: DependencyInstaller::GetInstalledFilename: Dependency 'linux_avcodec64' (37) is missing, installing
0035959: 140234557650880: Playback: DependencyInstaller::Install: Start
0035959: 140232263526080: Reader: CCurlINetReader::OpenRange: Start
0035959: 140232263526080: Reader: CCurlINetReader::OpenRange: Opening URL, Position 0
0035959: 140232263526080: Reader: CCurlINetReader::Close: Start
0035959: 140232263526080: Reader: CCurlINetReader::Close: This 7f8a60001bc0, CleanClose 0
0035959: 140232263526080: Reader: CCurlINetReader::Close: Finish (0 ms)
0035966: 140232263526080: Reader: CCurlINetReader::OpenRange: Elapsed MS 5.7638, initial number of headers = 0, number of loops = 0
0035966: 140232263526080: Reader: CCurlINetReader::OpenRange: Open Succeeded. Elapsed MS 5.7730, number of headers = 0, number of loops = 0
0035966: 140232263526080: Reader: CCurlINetReader::OpenRange: CURL open returned error value = 6, error = Error
0035966: 140232263526080: Reader: CCurlINetReader::OpenRange: Finish (6 ms)
0035966: 140232263526080: Reader: CCurlINetReader::GetInfo: Start
0035966: 140232263526080: Reader: CCurlINetReader::GetInfo: Finish (0 ms)
0035966: 140232263526080: Reader: CCurlINetReader::GetInfo: Start
0035966: 140232263526080: Reader: CCurlINetReader::GetInfo: Finish (0 ms)
0035966: 140232263526080: Reader: CCurlINetReader::GetInfo: Start
0035966: 140232263526080: Reader: CCurlINetReader::GetInfo: Finish (0 ms)
0035966: 140232263526080: Reader: CCurlINetReader::Cancel: Start
0035966: 140232263526080: Reader: CCurlINetReader::Cancel: Finish (0 ms)
0035966: 140232263526080: Reader: CCurlINetReader::Close: Start
0035966: 140232263526080: Reader: CCurlINetReader::Close: This 7f8a60001bc0, CleanClose 5
0035966: 140232263526080: Reader: CCurlINetReader::Close: Finish (0 ms)
0035970: 140234557650880: Playback: DependencyInstaller::Install: Downloading package failed
0035970: 140234557650880: Playback: DependencyInstaller::Install: Finish (10 ms)
0035970: 140234557650880: Playback: DependencyInstaller::GetInstalledFilename: Failed installing dependency 37
0035970: 140234557650880: Playback: DependencyInstaller::GetInstalledFilename: Dependency 'linux_libplacebo64' (53) is missing, installing
0035970: 140234557650880: Playback: DependencyInstaller::Install: Start
0035970: 140232263526080: Reader: CCurlINetReader::OpenRange: Start
0035970: 140232263526080: Reader: CCurlINetReader::OpenRange: Opening URL, Position 0
0035970: 140232263526080: Reader: CCurlINetReader::Close: Start
0035970: 140232263526080: Reader: CCurlINetReader::Close: This 7f8a60001bc0, CleanClose 0
0035970: 140232263526080: Reader: CCurlINetReader::Close: Finish (0 ms)
0035976: 140232263526080: Reader: CCurlINetReader::OpenRange: Elapsed MS 4.7865, initial number of headers = 0, number of loops = 0
0035976: 140232263526080: Reader: CCurlINetReader::OpenRange: Open Succeeded. Elapsed MS 4.7959, number of headers = 0, number of loops = 0
0035976: 140232263526080: Reader: CCurlINetReader::OpenRange: CURL open returned error value = 6, error = Error
0035976: 140232263526080: Reader: CCurlINetReader::OpenRange: Finish (5 ms)
0035976: 140232263526080: Reader: CCurlINetReader::GetInfo: Start
0035976: 140232263526080: Reader: CCurlINetReader::GetInfo: Finish (0 ms)
0035976: 140232263526080: Reader: CCurlINetReader::GetInfo: Start
0035976: 140232263526080: Reader: CCurlINetReader::GetInfo: Finish (0 ms)
0035976: 140232263526080: Reader: CCurlINetReader::GetInfo: Start
0035976: 140232263526080: Reader: CCurlINetReader::GetInfo: Finish (0 ms)
0035976: 140232263526080: Reader: CCurlINetReader::Cancel: Start
0035976: 140232263526080: Reader: CCurlINetReader::Cancel: Finish (0 ms)
0035976: 140232263526080: Reader: CCurlINetReader::Close: Start
0035976: 140232263526080: Reader: CCurlINetReader::Close: This 7f8a60001bc0, CleanClose 5
0035976: 140232263526080: Reader: CCurlINetReader::Close: Finish (0 ms)
0035980: 140234557650880: Playback: DependencyInstaller::Install: Downloading package failed
0035981: 140234557650880: Playback: DependencyInstaller::Install: Finish (10 ms)
0035981: 140234557650880: Playback: DependencyInstaller::GetInstalledFilename: Failed installing dependency 53
0035985: 140234557650880: Playback: CJRVideoPlayerWindow::LayoutWindow: Start
0035985: 140234557650880: Playback: CJRVideoPlayerWindow::LayoutWindow: Getting rectangles
0035985: 140234557650880: Playback: CJRVideoPlayerWindow::LayoutWindow: Failed to get video rectangles
0035985: 140234557650880: Playback: CJRVideoPlayerWindow::LayoutWindow: Finish (0 ms)
0035985: 140234557650880: Playback: CJRVideoPlayerWindow::OpenFile: Start
0035985: 140234557650880: Playback: CJRVideoPlayerWindow::OpenFile: Filename: /mnt/Movies/Ficção científica/Venom - Let There Be Carnage (2021)/Venom - Let There Be Carnage (2021).mkv type: mkv. CJRVideoPlayerWindow 0x55fab7076e00
0035989: 140234557650880: General: CMCUICore::UpdateScreenResolution: Start
0035989: 140234557650880: General: CMCUICore::UpdateScreenResolution: Default fullscreen settings:
0035989: 140234557650880: General: CMCUICore::UpdateScreenResolution: Using playback settings: Desktop Settings
0035989: 140234557650880: General: JRMonitor::UpdateInfo: Start
0035990: 140234557650880: General: JRMonitor::UpdateInfo: Screen width = 3840 height = 2160 x = 0, y = 0, rrmode = 35
0035990: 140234557650880: General: JRMonitor::UpdateInfo: 1 non-zero size screens found
0035990: 140234557650880: General: JRMonitor::UpdateInfo: Finish (0 ms)
0035990: 140234557650880: Playback: CDisplaySettingsHelper::ChangeDisplaySettings: Start
0035990: 140234557650880: Playback: CDisplaySettingsHelper::ChangeDisplaySettings: Current Mode: 0x0x0x0, Target Mode: 0x0x0x0
0035990: 140234557650880: Playback: CDisplaySettingsHelper::ChangeDisplaySettings: Finish (result: 1) (0 ms)
0035990: 140234557650880: General: CMCUICore::UpdateScreenResolution: Finish (0 ms)
0035990: 140234557650880: Playback: CJRVideoEngine::Open: Start
0035990: 140234557650880: Playback: CJRVideoEngine::Open: FFmpeg DLLs are not available.
0035990: 140234557650880: Playback: CJRVideoEngine::Open: Finish (0 ms)
0035990: 140234557650880: Playback: CJRVideoPlayerWindow::OpenFile: Failed to open JR Video Player
0035990: 140234557650880: Playback: CJRVideoPlayerWindow::OpenFile: Finish (4 ms)
0035990: 140234557650880: Playback: CJRPlaybackEngine::StopInternal: Start
0035991: 140234557650880: Playback: CJRVideoEngine::~CJRVideoEngine: Start
0035991: 140234557650880: Playback: CJRVideoEngine::~CJRVideoEngine: Finish (0 ms)
0035991: 140234557650880: Playback: CJRPlaybackEngine::StopInternal: Finish (0 ms)
0035991: 140234557650880: Playback: CJRPlaybackEngine::StartPlayFile: Play returned: 0
0035991: 140234557650880: Playback: CJRPlaybackEngine::StartPlayFile: Finish (31 ms)
0035991: 140234557650880: Playback: CJRPlaybackEngine::Play: StartPlayFile returned 0
0035991: 140234557650880: Playback: CJRPlaybackEngine::Play: Finish (32 ms)
0035991: 140234557650880: Playback: CPlayerZone::PlayNextFile: bCanPlayNext=0, m_bPlaybackError=1
0035991: 140234557650880: Playback: CPlayerZoneDisplayInfoUpdateThreadPause::~CPlayerZoneDisplayInfoUpdateThreadPause: Start
0035991: 140234557650880: Playback: CPlayerZoneDisplayInfoUpdateThreadPause::~CPlayerZoneDisplayInfoUpdateThreadPause: Finish (0 ms)
0035991: 140234557650880: Playback: CPlayerZone::Play: Finish (57 ms)
0035991: 140232263526080: Playback: CPlayerZoneDisplayInfoUpdateThread::Thread: Start
0035991: 140232263526080: Playback: CPlayerZoneDisplayInfoUpdateThread::Thread: Zone: Video (id: 10001)
0035991: 140232645514944: Playback: CPlayerZoneDisplayInfoLoadImageThread::Thread: Start
0035992: 140234373199552: Import: CWatchFoldersThread::Thread: Wait result (1)
0035992: 140234373199552: Import: CWatchFoldersThread::Thread: Found changes
0035992: 140234373199552: Import: CWatchFoldersThread::Thread: Found changes in '/mnt/Movies/Ficção científica/Venom - Let There Be Carnage (2021)/Venom - Let There Be Carnage (2021).jpg'
0035993: 140234373199552: Import: CWatchFoldersThread::Thread: Success (looping again)
0036028: 140232645514944: Playback: CPlayerZoneDisplayInfoLoadImageThread::Thread: Image: 00007F8AB8010780
0036028: 140232645514944: Playback: CPlayerZoneDisplayInfoLoadImageThread::Thread: Finish (36 ms)
0036067: 140234557650880: General: CMCUICore::SystemPowerManager_UpdateActions: Start
0036067: 140234557650880: General: CMCUICore::SystemPowerManager_UpdateActions: UI Mode: -994; Playing: 1
0036067: 140234557650880: General: CMCUICore::SystemPowerManager_UpdateActions: Disabling screen power and saver for Theater View (based on user option)
0036067: 140234557650880: General: CMCUICore::SystemPowerManager_UpdateActions: Finish (result: 12) (0 ms)
0036067: 140234557650880: General: CSystemPowerManager::ApplyActionsToSystem: Setting screen saver off (timeout=0)
0036070: 140234557650880: General: CSystemPowerManager::OnCmd: Screen Saver Reset
0036070: 140234557650880: General: CSystemPowerManager::OnCmd: Screen Saver Reset
0036070: 140234557650880: General: CSystemPowerManager::OnCmd: Screen Saver Reset
0036070: 140234557650880: Playback: CPlayerZone::Stop: Start
0036070: 140234557650880: Playback: CPlayerZoneDisplayInfoUpdateThread::Destructor: Start
0036070: 140232263526080: Playback: CPlayerZoneDisplayInfoUpdateThread::Thread: Finish (78 ms)
0036090: 140234557650880: Playback: CPlayerZoneDisplayInfoUpdateThread::Destructor: Finish (20 ms)
0036090: 140234557650880: Playback: CPlayerZone::Stop: Checking for not loaded playback engine
0036090: 140234557650880: Playback: CPlayerZone::Stop: Firing stop to playback engine
0036090: 140234557650880: Playback: CJRPlaybackEngine::StopInternal: Start
0036090: 140234557650880: Playback: CJRPlaybackEngine::StopInternal: Finish (0 ms)
0036090: 140234557650880: Playback: CPlayerZone::Stop: Processing internal previous / next
0036090: 140234557650880: Playback: CPlayerZone::Stop: Clearing display info
0036090: 140234557650880: Playback: CPlayerZone::Stop: Updating statistics
0036090: 140234557650880: Playback: CPlayerZone::Stop: Updating playback state
0036090: 140234557650880: Playback: CPlayerZone::Stop: Updating UI
0036090: 140234557650880: General: CMCUICore::UpdateScreenResolution: Start
0036091: 140234557650880: General: CMCUICore::UpdateScreenResolution: Default fullscreen settings:
0036091: 140234557650880: General: JRMonitor::UpdateInfo: Start
0036091: 140234557650880: General: JRMonitor::UpdateInfo: Screen width = 3840 height = 2160 x = 0, y = 0, rrmode = 35
0036091: 140234557650880: General: JRMonitor::UpdateInfo: 1 non-zero size screens found
0036091: 140234557650880: General: JRMonitor::UpdateInfo: Finish (0 ms)
0036091: 140234557650880: Playback: CDisplaySettingsHelper::ChangeDisplaySettings: Start
0036091: 140234557650880: Playback: CDisplaySettingsHelper::ChangeDisplaySettings: Current Mode: 0x0x0x0, Target Mode: 0x0x0x0
0036091: 140234557650880: Playback: CDisplaySettingsHelper::ChangeDisplaySettings: Finish (result: 1) (0 ms)
0036091: 140234557650880: General: CMCUICore::UpdateScreenResolution: Finish (0 ms)
0036091: 140234557650880: Playback: CPlayerZone::Stop: Applying database changes
0036091: 140234557650880: Playback: CPlayerZoneDisplayInfoUpdateThreadPause::~CPlayerZoneDisplayInfoUpdateThreadPause: Start
0036091: 140234557650880: Playback: CPlayerZoneDisplayInfoUpdateThreadPause::~CPlayerZoneDisplayInfoUpdateThreadPause: Finish (0 ms)
0036091: 140234557650880: Playback: CPlayerZone::Stop: Finish (21 ms)
0036091: 140232263526080: Playback: CPlayerZoneDisplayInfoUpdateThread::Thread: Start
0036091: 140232263526080: Playback: CPlayerZoneDisplayInfoUpdateThread::Thread: Zone: Video (id: 10001)