Maiden of the Mist AI Gets lost

If Yorick summons the maiden of the mist behind a tower that cannot be attacked, that is a tower that's outer-more tower hasn't been destroyed, the AI for the maiden will get lost, not following Yorick out of lane after the dive. She'll basically stand still, and do nothing once she loses her target.

I've not attempted to replicate the bug but it should be as easy as farming Yorick to six in a custom game and casting his ult behind a lane's second tower while the first tower is still up.