[Becomes immune to damage] All Rare monster in Abyssal Depth

Good day.
Today, when we first entered the depths of the abyss, we encountered a problem that all rare monsters did not receive damage. At some point, for 1-2 seconds, they hung up and could receive damage, but then again received immunity to damage for 10-20 seconds.
Here is a link to a video demonstration of the bug -
https://cdn.steamusercontent.com/ugc/17998524108229032804/D37C97FF1A81B02D654FAED1BC8DF5351BE1FDA8/
https://cdn.steamusercontent.com/ugc/16150181027276144437/85585CAE56A8B01768B19E64B8EFCA5C30B2FFDE/

For the second one i don't think it's a bug, you need to stand in the big fog to deal damage

As you can see from the video, sometimes damage would occur even when we weren't standing in the fog.
(You may also notice that they are constantly being drained of essence, but the energy shield still starts to recover and damage stops occurring)
I also attached a video of a fight with only 2 mobs, but if necessary I can attach 4-5 more videos of fights with other rare mobs, they had the same problem.
The only thing we could notice was that if we were standing close and not moving, they become vulnerable to damage more often than if we were standing far from each other.
P.S. He ended up killing us :C