Hello Richard and welcome to the community! M2 is probably at the end of your file and it resets the workspace and a bunch of other stuff. You can read about it and some possible workarounds in this thread.
In particular KGN mentioned this page in the docs for a workaround and that’s what I would probably try if the workspace changing was a problem for me.
Note that the interface to gSender has changed since those docs but there is still a place to put that code under Program Events in the ‘Cog Wheel’ settings. I would put that code in Program Start and Program End and run a short test job in the air, just zero Z up high, and see if it works.