In Zul'farak there is an MMap problem - on top of tower/pyramid where executioner is and Sergeant Bly. When you free him and company from their cages they can't get down from cages location, even if they want to go down.
In Shattered Halls (the ogre boss, forgot his name) has MMaps problems, he can't climb the stairs, so he can be easily killed from top of the stairs.
Here is a link what stairs I mean, and which boss. skip to 3:35 https://www.youtube.com/watch?v=ZjJxvqwibsk