Lightroom Classic 14.1.1 on Mac Os 15.1.1 Sequoia fails to back up on exit

Lightoom Classic 14.1.1 on Mac Os 15.1.1 Sequoia fails to back up on exit , and none of the answers here work! I have tried everything (not a permissions problem!) This is the second time this has happened and the only way I was able to fix it last time was to create a new catalog and ire-import 75K images. Very annoying! Not a good solution. Backups are very important as too many times i've had to rely on them when a catalog becomes corrupt, which happens far too often. Is there any solution short of exporting/importing and/or creating a whole new catalog? Capture One is becoming more and more appealing.