Should the default PMDG 737-700 stairs be disabled for GSX pro to work correctly. GSX seems to spawn it's own stairs below the PMDG one?
When you activate GSX with a PMDG airplane, it will send away all default PMDG vehicles first, operating the secondary FMC (so it won't interfere in case you are working on the primary one yourself)
If you are starting from a Cold&Dark cockpit, that might not work, because I think the 2nd FMC requires some power to operate.
A better solution is sending the PMDG vehicle away yourself, then use the Panel "STATE SAVE" option, to create a new panel state named "GSX", which you can call or even make default, so you won't have to wait about 30 seconds before boarding for the PMDG vehicles to go away.
