Cannot complete Golems of Amgarrak DLC (Glitch) Xbox 360 *Edit: Fixed*

Hello,

I am playing the Golems of Amgarrak DLC and am unable to finish it. The boss (Harvester) always becomes stuck in a wall and I am unable to target it (it isn't even selectable). This makes it impossible to finish the game.

Has anyone else experienced this, or has any suggestions?

Edit: Got it on the third attempt. In case anyone else has the same problem, it's best to kite it away from that side of the area, and keep as much damage on it as possible so it can't jump back over there. Even then, it's a case of luck.