@a6ff0b2b could it be that it’s actually still a “software”issue somehow related to an attribute specific hardware?  

Something like a poll rate out the mouse not being able to be handled correctly when other systems are “in process”?

Can’t think of anything that could possibly make it happen only if there are other visible windows if it was just a hardware bug. 

(Caveat: I’m just a Python programmer- I have no idea what I’m talking about) 

 @28a8ce2d Maybe macOS communicates back to the mouse via USB when it's going to reposition the cursor, like it does when dragging one window near another in macOS?