Bug Report ID: #2273665650. Vastweld, the Colossal Guardian.

Fight initially started fine, I was hitting the boss and he was able to damage me. Then at about 85% boss health, my minions and my spells could not damage the boss although he continued to fight and do damage. I logged out to Character Select screen, relogged back into game and re-entered the boss arena. At this point, the boss was still damaged and not reset back to full health. This time around, I still cannot damage the boss and he is not attacking me either.