BUG: Sometimes culling (Marked for Death) isn't working in 3.21.0c.hf4 against map rare monsters

It's happened enough times to notice: culling doesn't seem to working consistently on some regular map rares.



You can see here this mob is afflicted by my mark (Sniper's Mark). There were no other visible mobs in the area.



And I have "Marked for Death" allocated on my passive tree.



I also have Marked Enemies Cannot Regenerate Life allocated, so this shouldn't be a case of the mob quickly regenerating life above the cull threshold.



I expect culling strikes not to work if Berseker is still a possible monster mod in the game. But I don't see that mod at all on this mob. To verify: I am not wearing any gear that would prevent a kill unless certain criteria are met.



Is it possible some regular (and maybe crucible too?) monsters have hidden mods applied to them? Or.. is this just yet another bug, in which monsters are getting Archnemesis mods, where they should not? Or.. something else entirely?

I have seen culling work, it just doesn't work all the time.. as if the monsters sometimes have the Berseker mod applied or the mastery is just broken.

Please investigate.

Thanks!

Edit 1:

It appears yesterday someone else posted a similar bug that non-direct damage (ex: totems) is not culling marked mobs. In my case, I am doing direct damage with Lightning Arrow and still culling sometimes does not trigger.

so is this acknowledged? I feel like i should respec at this point.

-regards, the totem dude

friendly bump after recent patch notes. apparently cull works if mark is applied to enemy with <10%hp (not extensively tested)

Disappointment with how this is being handled

This was finally acknowledged by GGG, a month into the current league.

https://www.pathofexile.com/forum/view-thread/3375476#p24986788