I'm vaguely reminded of something similar: in one of the beta releases, my archer could remain sneaked even as she fired off arrows as long as she stayed out of the enemy combatants' sight cones, but at some point this changed where sneak would immediately be cancelled upon entering combat even if she was theoretically capable of remaining unseen. I always assumed it was a deliberate design decision to prevent mowing down an entire group of enemies using a sniper. Which I found a bit of a shame, but I can see why some people might object!
