Originally Posted by RobOnLI

Very likely related to the GAs manually writing down who is on the upgrade list and then walking on the plane and asking them if they want to move up. Given that the rate of people declining upgrades is super small the GA probably only wrote down the first 2-4 names on the list. Since everybody declined they closed the door and off they went. The other option was for them to walk up to the computer, get the next few names and go through the process again. The GA made a valid attempt to upgrade people and when they all declined the flight was closed and dispatched. Very normal. The GAs are not given handheld devices like the onboard crew so they can't see the upgrade list in this situation.

-RM