Bilial lair boss spawn has to be bugged, right?

I can’t get him to spawn anymore. I have him at 80% with ashes, nothing. When I first put them in, he was spawning almost everytime, now…nothing. He has spawned once in 20 runs in t3 and once in t4. I did over 100 runs with a friend and not one time did he spawn. We both opened the chest in time.