When I was ready for push back I only received 'parking options' on pressing Ctrl-F12.
If GSX think you are outside a parking, assuming you parked correctly, it's usually caused a conflict of AFCAD files. Check which AFCAD is used by GSX in the scenery customization page, and be sure it's the one that comes with the scenery.
If it's not, assuming you correctly put the scenery on an higher layer than anything that might conflict with it, try the "Restart Couatl and rebuild airport cache" option, and see if the correct AFCAD will be picked up.