Maybe this is old hat, I think they did something similar in the game last year too. But I played through the 16-ish pixellated floors of the event and then while I was killing some guys, it triggered the end game scene from the first diablo game. And that was it? There wasn’t a diablo to kill at the end as far as I could tell, it just sort of stopped. Just wondering if I missed something/something went wrong.
I think that’s how it was supposed to play out. At least that’s how I experienced the event. Shame we can’t go back.
Killing Diablo is what triggers the cutscene. Maybe you killed him without noticing? Otherwise, it’s a bug.