I have a bunch of files where the Genre is listed as Unknown. I've changed them to something else and back again but they still show as Unknown. I use MptTag to update the Tags. I just use Jazz, Blues, and Rock for my Genres. They are all files that were copied from my iPod, so they might be MP3's, MP4's, or M4A's. I am at Sever Version 5.1.
Thanks