I don't have any duplicate AFCAD, and never had a problem with the one that came with the scenery.
I never implied in you having a duplicate scenery. I only said that with the default scenery, the GSX follow me works normally so, the only possible explanation is there IS some kind of problem with the AFCAD that comes with this scenery.
And if "never had a problem", you are referring to never having a problem with the GSX Follow me at that scenery, that doesn't mean much, because different positions when you called it, and different gate destinations will result in different path chosen so, unless the scenery has tons of errors, it's very likely that you won't find any problem until the route chosen will pass through a problematic area.
Have you tried opening with ADE or AFX and ask for a "Faults report" ?