My gut is it's related to your system. The mouse is working for tens of thousands of S1 users, and if others were experiencing this same issue, you would see it posted here or other other support locations for S1.
There are plenty of other variables.
There are commands that don't work in some context. (For example: You can't "save" a file if nothing has been changed.) That said, it won't work with the mouse OR the keyboard when there is nothing to change.
You may need to post a video showing the behavior, as there is something special about your situation that is uncommon.