Here is a video showing whats happening. This is FSX Steam
The "Restart Couatl" option is currently not working on Steam, but of course this doesn't have anything to do with the fact that pushback doesn't start, just that you can't test it again twice (as a troubleshooting method) using that option.
The video is not very useful. What would have been useful, instead, would have been just a precise message indicating all the following:
- The airplane used. If it's not default, clearly indicate the model.
- The airport used. If it's not default, clearly indicate the scenery used and, if it's not a default or FSDT scenery, indicate if you customized it.
- The Gate used.
Taking a screenshot of the "Customize parking position" dialog from GSX might be useful.