I'm running mac os 10.13.6 on a 2012 mac mini and this has happened 8-10 times so far. I upgraded to MC29 from MC26 and never had these issues with mc26. I installed MC29 and added then opened the library I had been running from MC26 and things seemed to be ok. Unfortunately, so far I've had the following three disappearing scenarios:
Opened mc and the library I had been using (eg: Main Library - 2022-07-24) had disappeared from mc and been replaced with a new empty Main Library, no files, no settings.
Opened mc and the library I had been using (eg: Main Library - 2022-07-24) had disappeared from mc and been replaced with a new Main Library that included all of my files and some of my settings. Notably missing were the Auto-Import folder settings that had been working fine. - which just happened again-
Opened mc and the regular library is in place and seems ok but the Auto-Import folder settings that had been working fine are blank.
I've been patient and hoped the last update would fix it (currently on 29.0.87 from 08-17-22) or that I'd figure out what I'd been doing wrong but so far not-so-good.
Fortunately I've got TimeMachine in place. If I go in and replace the current versions of
users/me/library/application support/jriver/media center 29
users/me/library/preferences/com.jriver.MediaCenter29.plist
users/me/documents/Media Center 29/Library Backups/MC Library Backup (Main Library - 2022-08-20 09-20)
with a version from 2-24 hours ago (sometimes the timing is trial and error) and all is as it was and ok.
The second issue is that when quitting MC it will generally take 30 seconds to 5 minutes of the spinning beachball for the program to quit.
NowI presume it's on me and attribute some degree of culpability to my aging os and hardware, even though it's still in the supported status. I've been putting off buying new hardware until apple released a mac mini with the new M2 chip but I've caved and just purchased one with the M1 chip.