Stuck in campaign for a bug

Hi,
yesterday night i found myself confronting Kanu and the First Herald at the Excavation and managed to finish what i think to be the first phase of the boss but i was killed at the same time while he was changing phase. When i came back to the arena i found that the boss wasn't there anymore and there's nothing i can do to trigger the fight. My quest didn't upgrade on the journal so i found myself stuck unable to proceed with campaign. Do i have any options to continue with this character? Thanks in advance