One thing I've noticed and it has been like this for as long as I can recall is clicking on the refuel option in the GSX menu closes the menu 9 times out of 10.
You are making it sound as if closing the menu was the problem. The only problem I see here, is that is not closing it 10 times out of 10, because normally, whenever you select ANY option the GSX Menu will ALWAYS close, unless it needs to present you with an extra option, for example which operator to use for handling or catering IF there are multiple choices.
When you "activate" a gate in GSX ( first time you open the menu when you are parked there ), it WILL generate all its own Ground Vehicles around you, and this regardless which service you are starting with. To create the vehicles, it needs to know the handling operator so, regardless if you start with Boarding or Deboarding or Refueling or even just the Operate Stairs/Jetways commands, the first thing to do is knowing which handler will be used, so you will usually see a subsequent menu, asking which operator to use.
However, the operator selection menu won't always appear, if ( due to the scoring system and the eventual parking codes in the scenery or the airport custom profile ), when there's only ONE possible choice for the operator, that menu will be skipped so, after the first choice ( whatever it was ), the GSX menu will just close, waiting for the next command, because that's how the GSX is always supposed to work: it will always close after you made a choice UNLESS it needs to present a subsequent menu choice, like the operator.
This means, if you start with Refueling, and on that airport/gate there aren't multiple choice for the *handling* operator, the menu will close automatically, until it's time to ask your for the fuel quantity, which of course will NOT appear if the airplane is flagged as using a custom refueling system.
If you start with refueling and there ARE multiple handlers to choose from, you will see the subsequent handler selection menu after calling refueling.
If you start with another command ( like Operate Stairs ), the menu about the eventual handlers will be presented after you Operate Stairs, so it won't be asked again if you then call Refueling so, in this case, the menu will always close after choosing Refueling, because at that time GSX has nothing left to ask you, since the handler has already been set.
