Thank you very much for getting back to my issue!
No, the original value was not "Various Artists" -- see the screenshots below. As I said, this behavior does not seem to be limited to newly ripped files at this point. And I didn't change anything in the MusicBee settings for the last months (years?) to the best of my knowledge and this issue seems new.
So here is a "slide show":
1) This is what the automatic detection (correctly) figures out. I leave all tags alone and just hit "Start Rip".
2) This is the resulting album in my inbox, now mysteriously by "Various Artists"
3) The corresponding tag editor window
4) I change the Album Artist tag -- it makes no difference whether I just change one track or all tracks at a time. Changes are not applied.
5) I change a different tag -- here, it is the Artist tag.
6) Changes to Artist are applied, whereas changes to Album Artist are not applied.
