Genres can be in any order in Media Monkey meaning that Acoustic; Singer Songwriter will sort completely differently from Singer Songwriter; Acoustic. It is also possible that the genre tag contains duplicate genres.
I have written a small Media Monkey Add On that sorts and de-duplicates the genre tag for selected songs.
Download it from the link below, install it into Media Monkey by double clicking the downloaded file. The add on is provided without warranty.
Send me feedback and ideas for development.