Fire damage cannot cause poison with Avatar of Fire

I tried to build myself a BURNING ARROW build with Elementalist but I've met a weird condition with VOLKUUR'S GUIDANCE (FIRE) equipped. It does cause poison damage with all kind of fire damage source include Burning Arrow from my Xoph's Nurture, Wave of Conviction from Asenath's Chant and Rain of Arrow from Lioneye's Paw.

How do I know i can or cannot cause poison? The answer is Herald of Agony, it will buff me with Virulence once I cause poison.

But once i have the passive AVATAR OF FIRE, it cause me CANNOT CAUSE POISON from all my fire damage source anymore. It's weird, there is no description about Avatar of Fire preventing fire damage cause other ailments.

So I guess, this is a BUG right?

Nope, not a bug. Poison damage is still chaos damage over time and you cannot do any chaos damage, so your poison damage over time is zero. Therefore no poison damage stacks.

Of course i know poison was basically cause by chaos AND physical damage. But the function of Volkuur's Guidance is allow your fire damage do the same job as well while poison damage over time scale from your fire damage, as well as other item/talent/mod that let your fire damage cause other ailments.

But once I equipped Xoph's Blood that provide me Avatar of Fire(actually it's not needed since i deal only fire damage with Xoph's Nurture and The Signal Fire), it stop me getting any virulence buff from my herald of agony, I suspect that it stop me from causing poison.

Also, I tried to exchange some different gear and tick avatar of fire from talent tree and the problem still remain. So my conclusion is, Avatar of Fire is the one which preventing fire damage from causing poison to creeps. AND, there is no description talking about fire damage with Avatar of Fire cannot cause non-ignite ailments.

This is why I suspect either there is a BUG within Avatar of Fire OR description about this passive is wrong/missing.

"

Roseguy wrote:

AND, there is no description talking about fire damage with Avatar of Fire cannot cause non-ignite ailments.

Implicitly:

"

50% of Physical, Cold and Lightning Damage Converted to Fire Damage
Deal no Non-Fire Damage

You cannot deal chaos damage (poison) if you cannot deal chaos damage.

https://pathofexile.gamepedia.com/Avatar_of_Fire

And yes, the poison damage is scaled by the fire damage hit if you use those gloves. But the poison damage isn’t converted to fire damage. It’s still chaos damage.