Healers 'Prioritize Healing' bugged?

Hello there, first of all amazing game I already put 35 hours into it and am currently hunting achievements (the only thing missing is the last golden star on the last level in NG+).
Now, I have played some endless recently where usually the enemies at waves 50-60+ tend to hit extremely hard, that even the toughest lvl60 Knight with the best armor dies in a split second.
I have paid close attention to my healers and I have noticed more than once, when I set them to “Prioritize Healing” they will become very ineffective. Sure they still heal but somehow they completely stop everything else. They won’t use Zeal/Inspire or anything else. I have looked at 1/2x speed several times and when no one is hurt they just stand afk and don’t use their other spells. It must surely be some coding error? Because when I turn off “prioritize healing” they start buffing again. This shouldn’t be that way. Or rename the function to “Only heal and do nothing else”. Anyone else noticed this? it basically keeps me from using that function, even though everyone is dieing in those late waves because I don’t want to miss out on that +33% (or +49% for the healer wearing the special item) aoe buff.

Also, latest version on steam.

Confirmed in the latest test build as well. The healer will stand there, doing nothing - but he WILL cast Zeal on the first opportunity, meaning once somebody in his range is wounded, his first healing action will be Zeal.

How it should work, or how I thought it would work:

Healer will always use heal first, if that isn’t necessary he will always use his other spells, first Zeal/inspire then the 2 other aoe-dmg abilities.
The way it seems to work now is the healer does nothing when no one is hurt, and when someone is hurt he will first heal, then zeal/inspire or the other way around? either way it seems wrong. That is a really bad mechanic. And that means using that option highly cripples you.

He’ll use highest available skill for healing, which is Zeal.
Yea, it’s broken, a clear bug that Lars will undoubtedly address soon. (Bug 610 created)

Healer logic STILL broken?

Once more unto the breach, dear friends, once more!