The most common cases of a failure to regenerate the airport cache are:
- Antivirus interfering
- Any other kind of permission problem in the Community folder that affects your user account.
- Any other kind of permission problem in the OFFICIAL folder that affects your user account, which won't be fixed by removing the Community folder and, since you clearly can't remove the Official folder, a problem must be fixed at its root.
But the easiest solution, instead of trying to understand what's causing this, it's enabling the SU10 Navdata API option in the GSX Config panel, so it won't even use an airport cache and/or won't scan the Content folder for installed sceneries.
In addition to that, it will allow to use GSX on Marketplace airports.