I just ran into this bug and none of the fixes worked. What I found was if Braham is too far to the left wall of the tunnel when you initiate the Chak near the magister he will try to walk through the wall and become stuck. I was able to avoid him being stuck by engaging the chak with Braham more to the right wall of the tunnel when facing the magister, since he then has a clear path to the magister. Might not work for everyone since there doesn’t seem to be a solid fix for every situation. Best of luck!