So done this dungeon a few times now with the FC and the Second boss that requires you to kill the adds to get the stack to have hate on the boss works fine for the first 70% of the fight. However when the boss reaches 30% if the stacks go off the person with hate the boss freezes up and doesn't attack anyone or does any moves. He just sits there til he dies.
The game mechanics for that fight is the bosses hate will be on person with most stacks. When the person who has most stacks buff goes off the boss will switch to next party member with stacks on them. It works fine til the 30% mark in the bosses health. It's like the Twintania glitch when hate was supposed to shift and she would just sit there.