AIGTC creates a $PC$ Directory within the C:\Users\USERNAME\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache
In this directory there is also a "Community" folder included, which contains a Simobjects folder also. And in this Simobjects folder there are Airplanes, Models, etc.
That folder is not created by AIGTC, it's automatically created by MSFS itself, when you load an add-on that contains legacy textures, models or materials made for FSX, which are automatically converted by the sim into another format that is more suitable to MSFS.
So I think GSX PRO may have searched in the C:\Users\USERNAME\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache -> $PC§ Community folder, created by AIGTC and this may have caused an issue on wherevers addon??
GSX doesn't search in that folder, even if you have the SU10 Navdata DISABLED, because it only searches in the path specified in the InstalledPackagesPath line of the UserCfg.opt file, which normally points to %LOCALAPPDATA%\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\PACKAGES and contains Community and Official, the $PC$ is OUTSIDE that path, so it's surely not searched by GSX.
If you ENABLE the SU10 Navdata, GSX is not searching for ANY scenery in the Official/Community folder, it doesn't know or doesn't care which .BGL file you have, it just makes a Simconnect call to the sim to get the airport data about a specific airport, without having any idea where it's located in the filesystem, that's the whole point of using the Navdata: not having to worry about where the scenery is and which files contains it.
What fixed it in your case was just the Restart.
We have found a case where this happened, and it was airports with either no parking spots or taxiways which needed to be filtered out, a fix for this should appear in an update very soon, in addition to the already discussed "watchdog", which is an extra prevention against the other case, that is Simconnect just stop talking to us.