I am fortunate to have a mouse that works well 
and has no problem with it on my XBox (it’s a basic Trust optical mouse, connected thru an USB hub on the front port of XBox).
But even when it seems to work, we realize that the implementation of the mouse is not finished, poorly tested and that it had to be developed in a hurry 
.
Indeed, with my working mouse, there are still some bugs: for example, the cursor does not change when resizing or moving some windows (VFR MAP, NAVLOG), while it does with the XBox controller.
You can see it here, I opened another zendesk ticket for this bug, but it’s obvious that the mouse implementation on XBox is in ALPHA-TEST state, not finished, not tested.