Atziri fight cannot be finished

PS5 Pro (this is almost certainly irrelevant)
She's in her fell serpent form, very low health, standing there invulnerable, while lightning and blood novas are attacking me. Can respawn at checkpoint, even go to hideout and heal up and restore flask charges. Upon return to the fight, there is now a second Atziri, standing there, this one is apparently just a different, visual bug. Still can't do nothing to progress but in theory can drag this out to infinity. Guess I won't be opening those chests anytime soon.