Ok, I swear I'm not being sarcastic and there's no ill-will attached to this, but are you sure they aren't simply disabled from being damaged? I'm not assuming that you don't know that your robots can take damage and be incapacitated, but seriously, without actually seeing what you're experiencing, that's exactly what that sounds like. I had ADA getting her tail whipped for a good 2-3 hours last night, and I always knew when she went down because all hostiles immediately aggro'd in on me.
^^^This^^^ is absolutely the truth, and even though the companions jumping in front of you in combat has always been an issue, I've found that it seems to be even MORE so with ADA (for me anyways). Even when I'm sneaking, ADA just jumps right into battle and kinda ruins the element of surprise.