Coincidentally, I just posted this on Facebook. Guess I'll share it here too.
I think the Vault Bunker Door was intended to be closed and openable from one side only. Interestingly, the object's internal name is "Door_LockAndKey_Silo_02".
The patch only took it out of the editor, not out of the game. So, maps already referencing the object will continue to work with it in place. You just can't edit it anymore in the editor, as it doesn't know which object it should place there, You'll instead get an "Invalid Object" marker, depicted by a big question mark.
Here's what happens when you open it from "the unintended side", I guess that's the reason:
On a side note, this topic should move to the Editor forum. And there, it's also referenced by this thread.