I initially “added” artwork to a song via drag and drop, which did not work (no reason given.) I then added artwork to its entire album via the file browse feature.
And then I discovered a “2nd” instance of the song I’d attempted to add artwork to. Looking at the reported file paths, they each pointed to my original file albeit with irrelevant initial directories that don’t exist on my computer (and my computer is not the roon server) for the added file. We’ll just ignore for the moment how two identically-named files could exist in the same final directory, right?
So I carefully create a copy of the offending song file and move it away from roon. I delete the song in roon, and confirms that the ALBUM has been deleted from the hard disk.
I check the hard disk, which never had two copies to begin with and it’s fine but the 2nd instance appearing in roon is properly gone. Very little of this made any sense.