The GSX customization page will show the name of the .BGL read by GSX, which might give an idea of the issue.
If the default airport has been read, it's very likely parking positions won't match, so you need to figure out why the correct airport file hasn't been read, which should be indicated in the log, most likely case is the airport file is also larger than the maximum threshold to consider a scenery too big, which now defaults to 20MB.