The problem doesn't happen here, and nobody ever reported it before, and surely I cannot see how just entering/exiting from the parking editor without doing anything shouldn't make any difference.
The message about catering vehicles not available for this aircraft, seems to indicate that you either:
- Are trying to use an airplane that is not already internally supported by GSX without configuring it first, so you must configure it the first time you used it with GSX.
OR
- Are using an airplane that IS already supported by GSX, but configured it further, and made some kind of mistake while doing this. Using the "Reset" option in the airplane configuration editor will result in GSX removing all your customization and return to its default configuration for that plane, assuming it has one.
The airplane configuration page will also tell you if the airplane is already supported by GSX and if it's taking a configuration from a custom file you made.
Since you don't say which airplane was and whether you tried to configure it or not, I can only make those guesses.