Occasionally planes have other idiosyncrasies... engine has to be off on the Harrier for them to remove chocks. The ground crew are angsty about getting sucked up through that engine!
Happy New Year Skidders!
First step is to ensure the canopy is open - a lot of modules will not allow rearming refuelling with the canopy closed; you'll still be allowed to access the refuelling/ream menu, you'll laboriously make your edits and then... nada! This happens to me in the Mosquito a lot as I often forget to open the side window!