Unkillable Twilight Temple Boss

Twilight Temple spawned off of a Zana in a Primordial Blocks map. Have tried reloading the portals but cannot do any damage to him at all past 50% and he will not despawn.

Ive also experienced this bug, No idea how to fix it. Happen to me twice now, I think it's to do with phasing him too fast.

Its happen tome same thing but with legion boss(women with snake) and maligaro. I thought its related to me freezing them during phase. I am using frezing pulse. Legion boss has to retreat when he/she gets low but because of freeze they cant and stuck. So they dont drop loot. Normal map bosses became unkillable. You can damage their energy shield but life bar cant be damaged.

I'm having the same issue, but with the final boss of the map. I chose the fire portal, and the boss is stuck at 50% and won't phase or take any damage.

She continues to attack as normal.

I'm using Scourge Arrow, and I'm converting to cold, so I'm assuming I froze her when she was trying to phase.

Same issue here, but with Malachai in The Black Heart.

I can kill all the ads, but cannot cause any damage at all to Malachai, although I did remove his energy shield.

I eventually got him by creating a new instance and re-killing the 3 underlings.

Annoying bug though.

Same problem here with the final fight in the twilight temple. Fire boss spawned first and cannot be damaged to below 50%, but wont go to another phase either.
I am also using cold damage so freezing seems to be the issue.

I had the same problem. I tried to kill the moon boss but she became invincible after 50% hp. I wasn't gaining Vaal souls either, so she was definitely not taking damage. I was using a cold conversion scourge arrow. I tried switching to Rain of Arrows but that didn't hurt her either. She just kept attacking, wouldn't take damage, and wouldn't do anything out even if I left the map and came back.

Same here.

Using ice crash here, I believe this boss was frozen till half life, unkillable since then.

Same issue when I was fighting in Core.
https://www.pathofexile.com/forum/view-thread/2605548/page/1#p22264670

Having the same issue now in Blight league. Boss stuck at 50% health.