I've just installed your new GSX demo, all OK, then I closed FSX and restarted later, (my FSDT airports are Zurich, Chicago, KFLL, KORD, Honolulu), results:
no Couatl menu (but addonmanager OK)
NO BUILDINGS IN ZURICH (the only I've tested)
then I uninstalled GSX, reinstalled Zurich 2.5, reinstalled standalone, manager, BUT ALWAYS i become errors during standalone (or same Zurich 2.5) installation, see attached jpg
please help, thanks