iTunes stopped editing ID3 tags (again)

Time to time, iTunes loose ability to edit ID3 tags – they allow editing, but when I switch to a different track, I see the old info from the moment of adding to the library. I've got very extensive library of music and spoken word and I need to add new tracks (mostly MP3) from spoken word radio shows or other manually added tracks.

I use iTunes for organizing my audio files from day 1 in 2001 a there are some persistent glitches, but they could serve to the purpose of maintenance of the library. This dysfunction of editing tags happened first time back in 2018 after update of iTunes and since then it worked till the latest security update I've installed a few days ago. And the problem is back and it's really annoying.

– iTunes 12.8.2

– macOS 10.13.6 + updt/sec. 2020-02

– permissions seem to be OK on both places (I use just the iTunes library in ~/Music/iTunes and all the audio files are on 4TB external HD

– the distant location for audio files in iTunes preferences is also set up correctly

Any hint would be greatly appreciated. Thx.