Six weeks ago items began disappearing from the Finder Favorites list. It took 4 days for (14) Favorites items to be reduced to (4). Aside from the Desktop, User folder, Applications, AirDrop and Utilities, I only add folders from /Documents to the Favorites list. I followed the instructions found in similar Community posts: delete the Finder's plist and restart the iMac. The items that disappeared did not return on their own; I added them back manually. Situation stabilized until today: several recently added folders have disappeared.
I don't use any extensions, virus killers or “cleaning” applications. I use Disk Utility if I run into an exotic permissions problem. I don’t tinker with the system. When Safari begins to crawl I clear its history and caches and reboot the iMac. Occasionally I clear my DNS cache(s) via Terminal.
I think it would be useful to know what causes the Finder plist to become corrupted. Are there specific applications known to cause recurring corruption? Could it be something I do? How should I go about finding the cause of my problem?