Seems your initial problem come from the "Remove" instruction at Exit4 AND Service2...
From the manuel :
"This remove parameters instructs GSX to ignore this exit, and can be used to disable
all services linked to it. Removing a passenger exit will disable passengers stairs and will stop GSX from asking to open that door when boarding/deboarding passengers.
NOTE: the remove parameter should be used alone, without any other parameters on the same Exit section."
Regards,
Richard Portier