Please post here if you find that your healing Companion Character isn't doing their job and it isn't related to your pet. When posting, please provide as many details as you can and we'll be sure to investigate.
I have a better one. Recently, I've had problems where Khem Val would occasionally just stand around unless I manually order him to attack (and he's not set to stand-by either). As my sorcerer is quite squishy, not having a companion doing their share of the work can make class quests somewhat frustrating when this bug happens.
I've also had issues on my bounty hunter where companions just stop being automatically resummoned when leaving a vehicle.