As the title says...
On the final boss, when the boss is being shielded by the atronachs, one of them was out of position, above the rock near the walkway into the arena.
Could kill the other 2 as normal but the third would take no damage at all. We did kill the boss, but had to constantly take the shield down as well.
Could this be related to the bug that causes the mission giver to be floating in the air?
This is on Xbox.
Ran it on my other account, no problem, business as usual.