Boss - Crowbell "The Black Crow" - stuck at second phase

The Crowbell boss is stuck at the second phase.
Bug reference number is 556.319.488

What i expect to happen:

Damage Crowbell in the second phase until he leaves for the third stage arena.

What is happening:

The Boss is stuck hat ~5% HP and doesnt start the 3rd phase, loosing me the map completion.

I tried to:

leave the area with blink and come back
Portal out and back in

no change.