Bug? Fire mastery doesn't change the tooltip damage of Holy Fire

I was setting up a HF paladin an noticed that according to the tooltip, Ormus' Robes was worse than vipermagi for damage. After playing around with some stuff, I realized that the tooltip wasn't accounting for +%Fire damage at all.

It IS correct on the character tab, but I have no idea if the actual damage is being buffed correctly. Wasn't sure if there was a more appropriate place to report this, and I don't know if the issue applies to any other abilities.