Nightmare of Catarina unable to be damaged but still attacking

Bug report reference number 1,159,230,765

Was running a Ziggurat map and fighting Catarina when she should've moved to the third lich stage she just kept attacking me but is not damageable at all (no visible HP bar or anything on the screen anymore).

I tried re-entering the arena but she still just keeps attacking despite not being targetable by me or my totems.

EDIT: Actually just fought her again in a new map, and I may have killed the third lich in the one that bugged out. So maybe she should actually just be dead, but didn't actually trigger her death animation.