You can do a dead square shot at the clean room target, and the door still won't close. There were a few times that hitting the target prompted an "Immune" text to pop up. The explosion is so huge, it's a wonder that the game is having such a hard time registering the charge hitting the target. Also, even after you activate a clean room, you can still die somehow? That's pretty miserable. I haven't seen glitches like this since Crota. Updated with link of one instance of failure experienced today.