If the value "useAirportCache = 0" is in couatl_MSFS.ini in the %APPDATA%\Virtuali folder, GSX works perfectly for me in LSZH.
But not with useAirportCache = 1 (data for GSX comes from the airport.bgl)
You should not use the airport cache anymore and, since SU12, we automatically set it to 0, unless you explicitly override it, which you shouldn't do anyway, because without it, not only GSX won't work with Marketplace airports, but Jetways won't work correctly, since data about their actual position and points during the movement only come from the Navdata API since they are not found in .BGL.
There won't be any difference about how the Follow Me will work, so if you see any, it means you have a scenery conflict, most common cause is not having disabled GSX replacement jetways for an add-on airport, but in case of LSZH, not having disabled the default one.
While using the Navdata is clearly much better, it comes with more responsibility on your side because, when not using it, GSX only reads ONE .BGL at the time, so as long it found the right .BGL, it can't be confused by extra data from other conflicting airports, and it can also automatically associate an airport profile made for it.
When the Navdata is in use, GSX will get all data about that airport, including conflicts, and since we don't know from which .BGL ( or .BGLs ) this data is coming from, we can't automatically associate the "right" profile, so it's your responsibility to be sure you only have *one* GSX airport profile for that ICAO, and that one IS the correct one for that scenery, and you don't have any conflicts.