We tried this fight multiple times tonight and it appears that if anyone is on the center platform, or on the edge of the platform it causes Grym to glitch and not do his next move nor go towards whoever is he has targeted. He just stands there while his grey action bar just glitches. Also if youre on or edge of the platform and you recover from prone, your character is permanently glitched not allowing you to use any actions or skills.
We also found if someone had their weapon thrown off of them, they also became glitched and you cannot perform any movement, skills or actions.
