Armour applies to Elemental DMG vs Pyromantic Pact - does it work?

Pyromantic Pact - "When you reach max Infernal Flame, your Infernal Flame is set to 0, but you take fire damage equal to your maximum Life and Energy Shield. This damage counts as a Hit, but it cannot Stun."

Armour applies to Elemental DMG - clearly it should mitigate hit dmg from elemental hit, and since pyromantic Pact damage counts as hit, in theory it should mitigate it.

But apparently it doesn't?!

I have 144% of armour Applying to fire damage + 75% Fire resistance and if I'm taking armour conversion off - I still do receive same amount of dmg on a Pact trigger. So do I understand something wrong way, or it's simply a bug??

Anyone knows anything about it?
HALP!