If the scenery AFCAD has bugs or other problems, it's possible that GSX has rejected it. You can enable logging in the "Troubleshooting" section of the GSX Settings menu, and produce a Couatl.LOG file to verify this is the case.
You can also try to force a GSX cache rebuild, by removing the following folder:
C:\Programdata\Virtuali\Couatl
And see if the airport will be recognized on the next start.