I have almost the same problem after version 3.3.2.
After pushback and confirmation of good engine start, I can taxi a short while and then it stops. When I go back into the menu of GSX it still asks for confirmation of good engine start.
This has happened twice on the last 3 times I tried. There was one exception when at Geneva I disabled pushback at the parking spot, because I didn't need a pushback.
So, yes, I was able to recreate the same problem.
My PMDG 738 is up to date.