The King of the Mists fight bugged

Bug report number: 3 839 320 848

I fought the first phase. Than found the portal so far everything worked as always. But when I came back to the arena the boss is permamently in invulnerable state and not moving. Tried reloging and it didn't help. He is standing near the bottom left ramp.

Edit: just noticed I can't create a portal, the scroll is consumed but the portal does not appear not sure if that is intended.

Edit 2: happened again and this time relogging helped and was able to finish the fight.