The AFCAD that GSX is using is APX27150.bgl. I think GSX should be using the new AFCAD in the new scenery. Is there any way to fix this? The new airport scenery is excellent and I hate to use the default.
Is this new airport a "complete" and "self-contained" AFCAD ? If not, and it's instead a file that is supposed to enhance the default AFCAD, for example just adding new things, GSX cannot use it.
If you are sure this AFCAD is complete (meaning it includes runways, taxiways and parkings), then you can try the option to rebuild the airport cache in the Couatl Settings menu.