The patch seems to be breaking the DirectShow Filter Graph connections for video.
"0678328: 8700: Playback: CDXPlayerWindow::LayoutWindow: Graph doesn't have video interfaces"
But the Graph information in the logs looks okay, as far as I can tell.
Maybe reinstalling MC, and hence re-registering the DirectShow Filters, after installing KB4512941, will fix the problem? Or just try re-registering the filters manually on a non-working system.
A normal graph that plays properly on my Workstation installation of MC looks like the below. Perhaps check the Graph on a non-working system, if the right-click option still works.
=============================================================
Filter Graph Info:
Filter 'JRiver Audio Renderer'
CLSID: {A4002F8E-510F-442C-8AD3-F9C7B23FB394}
Host:
Input Pin 'In'
Connected to pin 'Output' of filter 'LAV Audio Decoder (auto-configured)'
Major type MEDIATYPE_Audio Sub type MEDIASUBTYPE_IEEE_FLOAT, Format type FORMAT_WaveFormatEx
Filter 'JRiver Subtitle Renderer'
CLSID: {F74E834C-9C98-43ED-89B1-19A9DF82E774}
Host:
Input Pin 'In'
Input Pin 'CC In'
Connected to pin '~CC Output' of filter 'LAV Video Decoder (auto-configured)'
Major type MEDIATYPE_DTVCCData Sub type Unknown GUID Name: {40FEFD7F-85DD-4335-A804-8A33B0BF7B81}, Format type FORMAT_None
Filter 'madVR'
CLSID: {E1A8B82A-32CE-4B0D-BE0D-AA68C772E423}
Host: C:\Users\rgi\AppData\Roaming\J River\Media Center 25\Plugins\madvr\madVR64.ax
Input Pin 'Input'
Connected to pin 'Output' of filter 'LAV Video Decoder (auto-configured)'
Major type MEDIATYPE_Video Sub type MEDIASUBTYPE_NV12, Format type FORMAT_VideoInfo2
Filter 'LAV Audio Decoder (auto-configured)'
CLSID: {E8E73B6B-4CB3-44A4-BE99-4F7BCB96E491}
Host: C:\Users\rgi\AppData\Roaming\J River\Media Center 25\Plugins\lav64\LAVAudio.ax
Input Pin 'Input'
Connected to pin 'Output' of filter 'JRiver Audio Monitor'
Major type MEDIATYPE_Audio Sub type Unknown GUID Name: {53544441-0000-0010-8000-00AA00389B71}, Format type FORMAT_WaveFormatEx
Output Pin 'Output'
Connected to pin 'In' of filter 'JRiver Audio Renderer'
Major type MEDIATYPE_Audio Sub type MEDIASUBTYPE_IEEE_FLOAT, Format type FORMAT_WaveFormatEx
Filter 'LAV Video Decoder (auto-configured)'
CLSID: {EE30215D-164F-4A92-A4EB-9D4C13390F9F}
Host: C:\Users\rgi\AppData\Roaming\J River\Media Center 25\Plugins\lav64\LAVVideo.ax
Input Pin 'Input'
Connected to pin 'Output' of filter 'JRiver Video Monitor'
Major type MEDIATYPE_Video Sub type Unknown GUID Name: {31435641-0000-0010-8000-00AA00389B71}, Format type FORMAT_MPEG2_VIDEO
Output Pin 'Output'
Connected to pin 'Input' of filter 'madVR'
Major type MEDIATYPE_Video Sub type MEDIASUBTYPE_NV12, Format type FORMAT_VideoInfo2
Output Pin '~CC Output'
Connected to pin 'CC In' of filter 'JRiver Subtitle Renderer'
Major type MEDIATYPE_DTVCCData Sub type Unknown GUID Name: {40FEFD7F-85DD-4335-A804-8A33B0BF7B81}, Format type FORMAT_None
Filter 'JRiver Audio Monitor'
CLSID: {A4207487-E7D8-406B-9882-B66370DE2492}
Host:
Input Pin 'Input'
Connected to pin 'Audio' of filter 'LAV Splitter (auto-configured)'
Major type MEDIATYPE_Audio Sub type Unknown GUID Name: {53544441-0000-0010-8000-00AA00389B71}, Format type FORMAT_WaveFormatEx
Output Pin 'Output'
Connected to pin 'Input' of filter 'LAV Audio Decoder (auto-configured)'
Major type MEDIATYPE_Audio Sub type Unknown GUID Name: {53544441-0000-0010-8000-00AA00389B71}, Format type FORMAT_WaveFormatEx
Filter 'JRiver Video Monitor'
CLSID: {A4207487-E7D8-406B-9882-B66370DE2492}
Host:
Input Pin 'Input'
Connected to pin 'Video' of filter 'LAV Splitter (auto-configured)'
Major type MEDIATYPE_Video Sub type Unknown GUID Name: {31435641-0000-0010-8000-00AA00389B71}, Format type FORMAT_MPEG2_VIDEO
Output Pin 'Output'
Connected to pin 'Input' of filter 'LAV Video Decoder (auto-configured)'
Major type MEDIATYPE_Video Sub type Unknown GUID Name: {31435641-0000-0010-8000-00AA00389B71}, Format type FORMAT_MPEG2_VIDEO
Filter 'LAV Splitter (auto-configured)'
CLSID: {B98D13E7-55DB-4385-A33D-09FD1BA26338}
Host: C:\Users\rgi\AppData\Roaming\J River\Media Center 25\Plugins\lav64\LAVSplitter.ax
Output Pin 'Video'
Connected to pin 'Input' of filter 'JRiver Video Monitor'
Major type MEDIATYPE_Video Sub type Unknown GUID Name: {31435641-0000-0010-8000-00AA00389B71}, Format type FORMAT_MPEG2_VIDEO
Output Pin 'Audio'
Connected to pin 'Input' of filter 'JRiver Audio Monitor'
Major type MEDIATYPE_Audio Sub type Unknown GUID Name: {53544441-0000-0010-8000-00AA00389B71}, Format type FORMAT_WaveFormatEx