Zalmarath, the colossus immune

I can confirm this. I'm stuck in act2 cruel as I can't hit the boss.

I had this bug happen. It started at 80% HP when Colossus moved and shot out red orbs. I am using poisonous concoction. When standing further away from boss than 25% of arena width, my attacks detonate at that 25% distance from boss. I cannot hit boss with projectiles. It is as if the projectiles are hitting a barrier (a similar range as the one that Colossus keeps its left arm and moves it around). When I get closer to boss than 25% of arena width, my attacks hit the boss but do nothing.

I have not had any issues prior to patch 0.1.1 and have used a variety of melee and ranged characters to fight this boss 15-20 times. This is the first time fighting the boss since the patch. I do know at some point (I think patch 0.1.1 on 1/17/25) GGG was going to make the Colossus's left arm untargetable (prior, it was the easiest spot to consistantly hit the boss---the boss's targetable areas are wonky). With the weird "barrier" taking up the same area as where his left arm is, and the timing, I wonder if something in the change caused the issue.

Had the same in normal and cruel too. Witch with a shitton of minions, few poisons too. My GF tried to solo it on normal with a ranger, no invulnerability stuff happened but when I tried to help her with my witch, it occured 3 times during the fight. When the boss moves to a new position, the state resets and you can damage it again until the bug happens again. Sometimes changes position every 40 seconds, sometimes it was standing for 5 minutes straight without moving... had to respawn to reset the fight