Rise of the Phoenix, Righteous Fire bug. Client shows full health, actually 35%

Tonight while in a Residence map that had the Elemental Weakness affix, I took a quick break before the boss and discovered this bug.

As the map's affix brought my fire resistances below the threshold needed to sustain Righteous Fury, I was relying upon my endurance charges to raise my resistances high enough to counter the skill.

However I took a quick break before the boss and my charges ran out. I started to lose health until I hit 35% when the "Increased Fire Resistance while on Low Life" affix from Rise of the Phoenix unique shield activated, which brought my fire resistance high enough to sustain Righteous Fury.

However rather than my health staying on 35% as expected, the UI showed my health continuing to regenerate until full. Looking at my characters defenses, it still showed that I still had the 'low life' fire resistances from the Rise of the Phoenix shield active.

Changing to secondary weapons, removing or changing armour (or getting hit by the boss or I assume any other enemy) updates your healthbar to the true value (35%), which would have been nice to know before charging into the bosses' room and dying to the first hit.

I have been able to repeat this bug on demand in the eternal laboratory by removing armour until I wasn't quite able to sustain righteous fury (but could with the extra resistances from Rise of the Phoenix).

Note: I was playing on Lockstep (Auto) but have also been able to repeat this on predictive mode.