Boss issues in the Titain Grotto

Me and my wife having issues with one of your bosses in ACT 2. Its in The Titan Grotto. Zalmarath the colossus. He will occasionally (more often then not) be untouchable. Auto-lock doesn't work and he takes no damage until he moves positions. Me and my wife are playing on line on separate PS5s and are both experiencing the same issues. Thank you for your help in advance. I also have recordings of this issue on my PS5 let me know the best way to get the footage to you if you require it.