Neither does it work without NoAI, this means mapmakers can no longer put custom names in the boss bars, how sad...
So, you mean that if anything is wrong, nothing is going to be solved? How nice for the mapmakers that depended on that, if that's the case, also the mobs just turn around as usual, only on the same block.
By the way, NoAI made them not fall, and ignore the motion tag before, there is also a very weird bug, when you give a boss mob no AI that boss' boss bar will not change ever.
Confirmed for 1.9 official release.