Iron Reflexes Keystone - Not Applying proper damage mitigation

Running through campaign on a Hollow Palm Ritualist with what the game tells me is an estimated 59% physical dps reduction from armour with 56% of it applying to all elemental damage as well, with approximately 1.1k life but still manage to get one shot by by monsters at a lower level?

Looking at how it works with the changes in PoE 2, I appear to be scaling it properly with increases to armour (on my stat sheet at least) so the numbers are there, but I believe the reduction is not being applied.

I've played through the campaign probably at least a dozen times this league on every melee class, have had less armour on both warrior and druid at the same level and have felt more tanky. I don't believe lower level monsters should be one shotting me through what (should be) a substantial amount of defense through the campaign. Can this please be looked into?

Mid act 4, still looking for upgrades to hit cap, but I'm sitting a little over 60% all res, 43% Chaos Res, Armour number shows as just under 2250.. Stacked all EV gear cause I went reflexes, and pathed over to warrior side of tree for nodes simar to prism guardian/armour against ele damage nodes