See error log attached, let me know if you need more information's.
The only thing unusual in your log, is that your packages folder is located here:
G:\WpSystem\S-1-5-21-1189416948-1545690038-2298426560-1001
Instead of here:
\Users\YOURNAME\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\Packages\Community\fnx-aircraft-320\SimObjects\Airplanes\fnx320
That seems to suggest some kind of problem, like having changed your user account after the installation, but it shouldn't affect GSX when using the Navdata API, quite the opposite in fact, if this WAS in fact a problem, it should affect GSX only when NOT using the Navdata API, because in that case GSX would require access to the Community folder and scan scenery files, something isn't doing when using the Navdata API.
The only relevant thing the log shows, is that GSX couldn't detect you entered in any airport. When using the Navdata API, GSX ask the simulator what's the airport closes to your location, but in this case, it couldn't find any. When using the Navdata API, we are in the hands of Simconnect providing with the correct data which means, if Simconnect doesn't respond or respond with null/invalid data, there's not much we can do about it.
Instead, when not using the Navdata, GSX detects the airport you are located in using its own code, looking at the airport cache it created be scanning your sceneries. But of course, in this case, since you are using a Marketplace airport, it would have found the default airport instead. Still better than nothing, but parking positions would likely be wrong.