First encountered the bug against the Boss version of "Penumbral Lurker". I will completely stop regenning any rage, getting entirely capped in willpower.
I am playing a build that is entirely dependant on rage, so i cant do anything. Potions gives me nothing. Blocking(getting hit) gives me nothing, which should give me 35rage.

Second time i met this issue, was fighting against the champion version of Penumbral Lurker.
I thought it was this unit creating the bug. But, just lost a 3map deep level 189 run to the same damn bug again. This time it was the big spitter boss doing it.

I tried running away from the boss to see what would happen. Nothing hitting me, no debuffs, still not regenning rage normally. It will come in small bursts, but then reduce itself down again to previous state. Potions give once again, nothing. My shout which also should give me rage, gives me nothing. Basically the damn regen system bugs out.

Following is a picture of the champion version of the second time i encountered the bug, and obviously lost the dungeon because i cant do shit without rage.
https://imgur.com/a/Kj9NCU4

The second picture is when i left the area of the spitter boss, trying to see if i could regen some rage. You will see no debuffs, nothing hitting me. And yet still no indication of any regen at all. Using potions will give me no rage.

https://imgur.com/a/Ce7y3Jc

I would give you the info of my character, what it is speced in and all that. But that would simply be too much of an effort.
I assume you can see it for yourselves by knowing my steam, and the character name from the pictures.