GSX is taking data from the simulator itself, it doesn't know anymore where it's coming from, which means:
- If you are using a GSX profile, it's your responsibility to be sure it's correct for that airport, since GSX can't chose it automatically based on the loaded .BGL because...there's no "loaded .BGL" anymore when the Navdata is used.
- Using the Navdata, will inherit any possible scenery conflicts you might have. A conflict might happen for many reasons, like the scenery not correctly excluding the default Navdata ( which might have been updated in the sim ), the scenery not loading in the correct order and possibly conflict by GSX jetway replacement files, but this not possible in this airport, since there's not jetway replacement file for that airport in GSX.
When using Navdata, it's your responsibility to be sure you don't have any scenery conflict. They usually can be spotted by seeing double parking spots in the World Map.
Lastly, the scenery MIGHT really have error, and I'm afraid with freeware this happens very often. In one case, where another user had the same problem with GSX reporting no valid data, it was caused by a missing runway->taxiway link in the scenery, which made the airport invalid and WAS fixed by the scenery developer.