Unearthed runecaster projectile (I guess elemental dmg) can bypass ES in expedition map

I am playing LL with shavronne's wrappings.
And I found something weird after I died from a white mob projectile which was unearthed runescaster in expedition map. After I died still I had ES left (around 5k) which means projectile dmg bypass my ES which should not be. I have tested this 4 more times. I lured a unearthed runecaster and let it one shot me.
Please check this.