As discussed many times on the forum, whenever you see the parking menu when you think you are on a gate, it's because of an AFCAD conflict: another scenery is conflicting with your scenery, so GSX is picking its own AFCAD instead.
Check the name of the AFCAD used by GSX, with the parking customization menu, and verify if it's the one which is supposed to be used for the scenery you are on.