I am having the same problem and it is making me nuts! It is also a hard thing to search for a solution to since the wording is tough to make unique.
I have removed all music from the iPad and then manually added music to a new playlist and then just brought that one playlist into the iPad. Same problem, song list is sorted by artist name.
Everything is OK in another iPad and iPhone, it is just this one iPad mini. I guess I'll have to reset it and not restore from backup to see if I can isolate the problem.