There's a couple conditional checks during combat that might be preventing them. If a character is locked in close melee combat, this is a possibility. It's to prevent the cleric from wasting the spell--moving in and gettinmg attacked as well. Unfortunately the scripting language isn't quite fine-detail enough to express this all properly. So sometimes combat healing gets cancelled out because too many enemies are too close to the recipient. Considering this, the 'best answer' is subjective. It would almost take a separate "combat medic" script (or a toggle on the healing switch maybe?), one that never bothers to worry about who might be harming them while they heal others, or if they waste their spells in the effort. We already have too many scripts in the set, but I'd consider making a toggle for it whenever I can devote a block of time to these scripts. More I think about it, probably not that hard to do.