The excacvation Boss bugged

I killed Benedict the First Herald and Died at the same time the boss died. I respawned at the last checkpoint, and he will say his dialogue: "My lady... You must take your leave. I will bury these fools... I will bury it all! for the Saviourrr!" He is in front of the gate and after he's finished he flies away and there's a NPC dead on the ground by the door, unclickable. the quest still says Confront Kanu and the First Herald.

I've tried to Relog, go to another map and get new checkpoints, respawn at checkpoint on the menu screen. I'm still stuck and can't progress.