It does show up (along with the addon-manager) in my add-on list in FSX, and i can go into the GSX settings menu, but the menu itself (where it says request boarding etc...) does not show up at all.
If you have both the Addon Manager and the "GSX Settings" menus visible under the FSX "Addons" menu, it means there's nothing wrong with the GSX installation and it's working fine.
Some reasons why you don't see the GSX Ctrl+Shift+F12 menu are:
- Another product has taken the keys used by GSX so, you must fix the conflict either from that addon (assuming it allows you to change its keys), or from GSX. Note that, some addons take keys in a non-standard (not using Simconnect) way so, for example, they might block GSX from working even if they used just F12 and GSX is using Ctrl+Shift+F12. We had reports Ezdok camera used to do this.
Sometimes it does work, but then i can't get the options (boarding etc...) because it says that there are no services at this airport.
This also is not a GSX problem but, a conflict caused by another scenery. You can check which scenery is used by GSX with the "Parking customization" menu. Some sceneries use auxiliary airports to represent seaplane bases, helicopter parkings, etc. so, they appear to be valid airports, but with no usable parkings. You can fix these cases as explained on the GSX manual, page 24.