Invincible enemies

Hello,

I have been coming across invincible void enemies. I have no idea what's causing the invincibility. The monster does not have the Amanamu's Void mod, and there is no other enemies around so no monsters with the Undying Will mod either. The only mod these monster have when i find them are Kulemak's Desecration. But that should not make the monster invincible right? The mod isnt even in an active state firing off the laser. In have come across this multiple times and there have only ever been 2 types of monsters that get this invincibly. The snake looking monster that pops out the ground, and the new large void monster with multiple tentacles. I just have to keep attacking the enemy hoping i wont die and hoping the monster will finally decide to take damage.