Thanks for the helpful replies above. I’ve “sort of” made some progress but have run into a different problem now…
I don’t have a backup/copy of the Audirvana database file (as suggested by RunHomeSlow), but I did manage to dig up a version of my Apple Music (iTunes) library file from Dec 2019. So I have a snapshot of my playlists from 7 months ago – recent changes to them made in Audirvana will be lost but this is probably a 90% solution for me. So that’s the “good news”. My plan was to export these playlists from Music and re-import them into Audirvana (that’s how I got them into Audirvana in the first place).
The “bad news” is that unfortunately importing M3U playlists into Audirvana doesn’t work for me. I saved one of my playlists out of Music, used the File > Import Playlist command in Audirvana, and nothing happens. The playlist isn’t added. I looked at the M3U file in a text editor and it’s clean, the data is there and uncorrupted.
I tried completely deleting Audirvana (and all its associated support files) and reinstalling it on my Mac Mini. This cleaned up some other minor issues in my Library like seemingly random duplicates and also occasional missing tracks which is nice, but importing playlists still doesn’t work.
I did some Google searching and found a few other posts here in the Forum going back as far as 2019 from other users having the same problem with importing playlists. Seems like it’s an open issue/unfixed bug.
Going forward I’ll make occasional backup copies of my Audirvana database file. But for now…Well, I guess I’ll head over to the other thread about the playlist import bug and make a new post there to see if anyone has new ideas/info.
Thanks again for the help here!