Hello,
Sometimes Nayat in her 2.Phase don't accept the white hit from the one with the most stacks, we had a issue that the player with 12 stacks could not activate the boss, anyways he died 2 times and we rezzed him , than we had the idea that the one with 2 stacks should try it before we retry the whole boss, and that actually activated the boss. I think there is a bug sometimes within.
Greetings