Tried the Learjet just now, and it doesn't happen, the Bus arrives and it *ask* to open the exit 1, then it open its doors, wait a bit, close its doors and goes away. Then the baggage loader arrives, pause for a few seconds, and goes away normally.
Maybe you simply had to wait for the baggage loader to arrive ? Have you been asked to open the door (if it was closed), when the bus arrived ?