not sure if user error or if surface pro 11 is incompatible with being primary computer

I'm having difficulty using my surface pro 11 with flex keyboard as primary computer, and my desktop as a secondary computer. 

For some reason, it works fine when my desktop is the primary computer with my wired mouse wired into the primary desktop, but when I try to reverse the situation - meaning plugging my wired mouse into my surface pro 11 and using it instead as the primary computer so that I can use my touchpad on the flex keyboard to navigate my desktop computer's monitors - the desired behavior fails.

This basically means my mouse is stuck on the surface pro 11 screen no matter if I use my touchpad or my mouse wired into my surface pro. 

My apologies if my explanation is a little convoluted, I could not see any other way to describe it.

I am available for further questions, have attached relevant screenshots.

Thank you for any help you are able to give,

Alan