In that instance, The GSX dialog was as if the engines had not been started.
I am still having issues and have opened another thread, but the problems are much the same.
Having flown and landed the GSX window would not open. I used panel manager and opened the Simconnect window, which showed GSX still in Pushback mode, I had the option to Stop PB or abort. Neither of which worked.
Seems that for me GSX will not finish the PB.