Playlists in Music disappear after a restart

Newly created playlists disappear after restarting the computer. This never used to happen, but it seems to have occurred after a recent update. This problem doesn’t occur when I create a playlist in another user account on the same computer. I don’t want to create another user account to beat the problem, I have had to do that in the past for other issues and it is a real bother.

I should add that I am not a subscriber to Apple Music, I never have been.

I have read about temp files being created in the application package. I see there are many under the preferences.plist file. Deleting them doesn’t help as they are just replaced after the next restart. In previous Mac OSs trashing the preference file was often suggested. Is that still an option?

From reading the many posts about this problem I see not many people get a satisfactory solution.

I wouldn’t mind if it were an occasional issue, but currently, no playlists are saved. There must be a solution somewhere. Any ideas, please?