Unkillable monsters

Its supposed to be a known bugs, but recently it appears often. Unkillable monsters appears specially after killing GRift boss. Its seams they were killed but remain in a ghostly presence - unkillable but they can do damage. This makes LGEM upgrade harder - having something hitting on you while doing the upgrade - thus stopping the upgrade. It start about a week ago - I never had this before (no change in my PC)

It just happend me today, “blue” elite die but dead body from one of them keep following me and dealing dmg (screenshot), but thats not all, when i run away and return back, his body was back as normal live elite and one more apear, when i run away again and come back its again just one, every time i run and come back one of them randomly apear and disapear.
https://prnt.sc/rojgsz