MAC: Genre tags differing between iTunes and Fuze?

I’m a Mac user who is trying to get my new Fuze set up.  So far, everything has worked, except that the some of the genre tags end up different on the player.  There’s no apparent rhyme or reason as to what gets altered, as far as I can tell.  I’ve been using iTunes to tag the files (all of which are MP3 format), and uploading them with with the player set on MSC setting.  The same thing happens when I copy the files to a MicroSD card independently from the device.  Any suggestions as to what I ought to do to sort this out?