As explained so many times on the forum, and of course on the manual:
- Your own airplane airline doesn't have any effect on the choice of the GSX ground or catering operators. It would be wrong if it did, since ground operators change by airport, your personal ground crew surely cannot follow you everywhere in the world.
- Your own airplane airline, instead, affects ONLY the choice of ULD containers loaded, because in this case, it's to be expected you'll use your own containers, and they should follow you from departure to destination. This works only if your airplane has its atc_airline_codes sets correctly in the aircraft.cfg file
- Sometimes you don't see the operator menu, which is normal, in all cases in which only once choice would be available, since no other operator had the highest score for that airport/parking combination.