After initial load, problems will intermittently occur, mainly when checking the map and going back to gameplay. This causes any UI pieces to lose their values, no longer read "mortal coil" with image, just a blank square. This is the same effect when you load an area.
I have tried it in the areas for Cata, Vanilla, and BL. This happens in all the areas including the main cities. Gameplay is possible during the transition from faulty UI to complete, but experience is greatly dimished.