The Black Barya boss disappears and doesn't return

Bug Report ID: #4,085,326,848

At the 50% phase, I left the platform before the channeling black mess starts. The boss never started channeling. Returning to the platform, the boss had disappeared. There was still one monster remaining on the Map. There were no items on the ground. I left and returned and the boss still did not re-appear.

Exact same thing happened to me. I burned the boss down to about 40% before he went invulnverable, right as he summoned the pillars you run through. I ran through the pillars, and then frostblinked to the outer ring. The boss disappeared and never came back.

Same ... bye my 165 chaos to buy the item to summon it

same ,didnt blink or walk anywhere , stayed in one place.