When you are using the SU10 Navdata option, GSX will take every data from the simulator itself, which means if you have a scenery conflict, it will get that one too, conflicts included.
Instead, when you are not using the SU10 Navdata option, GSX will read only a single .BGL at a time so, assuming it read the correct .BGL for that scenery, it won't be confused by other conflicting sceneries.
The two most probable causes of conflicts to LSZH are:
- the default Microsoft LSZH, which must be deleted from the Content Manager and NOT manually, otherwise it will be automatically re-downloaded at the next start.
- the GSX own jetway replacement files, which must be disabled at LSZH, like any other non-default airport. The automatic disabling is done when you first install GSX, when you run a GSX Update, or if you enter the GSX Config panel and press the "Disable 3rd party" button there. Check LSZH is on the Disabled airports list and not in the Enabled list.