Sorry, I wasn't clear enough "Isolated" is not something you can judge visually.
It an error in the programming of the airport, usually means a parking spot is not connected to the rest of the taxiway layout, which for GSX is unusable ( it will create problems with AI as well ), since ground vehicles can't reach it.
So, it can't be checked visually, but only by opening the actual .BGL with some tool showing the airport structure. That's why I asked if other parking spots work.