I realize this problem has been discussed many times, but I have tried all of the suggestions unsuccessfully. I have many sub-genres that I can't get rid of, illustrated by this screen shot.
Configured the Tag Panel to only show user defined genres.
Changed or added genre field in Extended Tags.
When I take these steps Mp3Tag shows the genres correctly, but no matter what I do, when I look at the directory in Windows Explorer the bad old genres have returned.
After I finish blanking the genre field and changing the genre to one of the user defined genres, it looks right in MP3Tag. But if I close MP3Tag and go back the the finder, the first screenshot I posted shows incorrect genres; my changes don't stick.
This is again what MP3tag shows for the directory:
What does the extended tags dialogue look like after you have made the changes?
Right now it looks like every program shows accurately what can be found in the files.