Why is the Chaos Pierre crashing my pt?

I was with some people, we were trying to kill Chaos Pierre(i would say got damage to kill him, it's more about surviving in there), so we were there and sudden all the pt crashed and dced :f6:, why? Maybe because we are killing it fast?(Pierre made the strongest in the pt attack him some times) or what?:f6:

note:my pt had a Bishop, a Night lord, a Dual blade, a Demon Slayer and a Phantom(if it's a glich of a class maybe it can help).
Help plz :f4:, it's really annoying to get this crash sometimes.