When your shelter is under attack or a room is on fire, your game enters a different state or mode. During this mode, you can move dwellers around to reinforce different locations. When the incident is over, your dwellers return to their original assigned area. After further investigation I believe I have found a bug in regards to this game mechanic.

During an incident, if a dweller dies and is revived the dweller will of course continue to defend the assigned area but because the dweller was revived during the incident, the dweller will be unassigned from that location. Unless you revive the dweller after the incident occurs, the dweller will stay assigned to the given area.

I think this bug was over looked when implementing this mechanic and should be patched because this can cause chaos and frustration if more than 10 dwellers are revived then unassigned from their location. The player will spend their time fixing their dweller assignment than actually playing the game.

I think "fixing dweller assignment" is actually how the game is played.

As for the "bug" presented; Its been documented before and I don't know if its a bug or by design. Personally, I think its a non-issue since they only assume the coffee break assignment and don't mess with existing ones.