The desktop mac client loads the Plex logo and then goes to a blank screen. If you hover the mouse in the correct area the mouse cursor will reflect that you’re hitting an input area but it’s completely hidden and not useable.
The same client works fine on a macbook pro (same version of MacOS (12.4) but doesn’t work on a Mac Pro with AMD FirePro D500 graphics.
Reporting that this worked for me for the regular Mac client. However, the new HTPC client for Mac behaves the same way - black screen. I did the same thing to the ini file ~/Library/Application Support/Plex HTPC/plex.ini but it does not fix the HTPC.
HTPC doesn’t allow disabling of the GPU acceleration because it won’t work without it. Unfortunately this really comes down to a case where Apple needs to fix their OS/Drivers which we all know will never happen.