I'm having this problem too submitted a ticket Thursday and its not been closed or vanished just not looked at by anyone at all it seems. I got 56 costumes setup and can only access the top of my list without a tailor which defeats the point in having them. Not very happy about this at all. HOW HARD WOULD IT BE to put a slider on there when you have more than a certain # of costumes set up.
This was supposedly fixed in today's patch but its still broken. The selection box is now tiny but the list scrolls down to the very bottom of the screen (Still showing the same limited selection) and I cant make it scroll at all . Really disappointing.