Cannot damage Belfry boss (probably when completing Vaal side area in between(

Had a Kirac (T16) mission to complete Vaal side area in Belfry map. Went first to boss and died at the same time / just before when "Hearth phase" started.
After hopping back in the map I completed the Vaal side area before going on the boss.
When re-engaging the boss I was able to kill minions and deal with the hearth but boss didn't get health bar back and didn't take any damage. After hopping out and in few times through portals the boss health bar reappeared and I was able to finish the boss.


In the screenshot health bar had reappeared.

Bug number 3 928 572 668