Cuachic Vault - Boss refuses to fight me on retry

Experiencing a weird bug. So, in the cuachic vault in the interludes. I began the fight with the 2 blood priests. First time, defeated the sister. Before I could kill the brother, I got oneshot by an offscreen laser beam.

Since I'm on softcore, I restarted at checkpoint. Went back into the boss room, and now the 2 are just endlessly screaming at each other in Vaalish. One is doing the blood ritual animation, the other is kneeling over as if defeated. Either way, the boss fight doesn't start. Sat here for a good 10 minutes watching them yell at each other, it's kind of funny.

Tried walking all around the room, into them, firing spells at them - nothing. Respawn at checkpoint didn't fix it either.

I assume I have to reset the instance to retry the boss fight. But it's a bug nonetheless.

Can confirm, I'm experiencing that right now. I have to keep making new instances to retry.