Works perfectly fine here, with the PMDG 738-800, using the same gate, same airport and same profile you attached.
Are you using AI traffic injection ?
This scenery seems to be extremely dense and very hard on fps (even with GSX disabled, that is shutting down Couatl), perhaps it just has too many objects and, combined with AI traffic, it reached the maximum number of objects available in the sim, after which Simconnect starts to behave erratically, which will of course cause all sort of issues to GSX.