Mule has a too large model

The mule I bred with a white horse and a donkey looked grown up from the time it spawned, but was not rideable. I can feed it apples/wheat and this seems to decrease the size of his shadow to the size it is supposed to be but the model stays the same. The mule is not rideable and for some reason the game points me south when I try to mount it.
(only tested on server)