u/BhaamLachez

My vault was attacked by deathclaws and I had grabbed a dweller to the vault entrance as to serve as a first line of defense, but the deathclaws were too quick in destroying the vault door and were into the entrance before my dweller, so I grabbed him back to his production room, and then... the deathclaws did not move from the vault entrance, while attacking and being attacked by the dwellers in said production room. And that lasted until the last of them was dead, without them roaming around in my vault.

That's the first time this happened to me. I don't know if it is a known bug, but if it can be reliably triggered, it would be fairly great, by allowing the attacks to not last too long as you can block the attack into a single room until it ends.