Crystal Ore Bugged Boss

Last remaining boss in Crystal Ore is invincible. I was farming essences in a t6 with a character who does around 100 million DPS, so I suspect I killed the other two bosses too quickly and the invuln phase they share bugged out. It was the Champion of the Hollows that was invulnerable.

Looks like this bug was reported back in 2022, so I doubt it'll be looked into, but w/e.

https://www.pathofexile.com/forum/view-thread/3269147