After installing 1.2 I'd played for a while and went back to my house in Markarth and just happened to notice that my Thieves Guild armor was no longer showing on my mannequin. The mannequin is now offset but can still be activated and the armor is still there but I can't see it.

This happened to me before 1.2 with my Falmer gear. I just took it out of the mannequin's inventory and put it back in. It's been working fine ever since.