Using Windows 10… when I alt-tab to other applications and then back to Mixxx, the mouse pointer completely disappears and will not come back.
Do you have it enabled as a controller?
Yes it works fine at first. It just randomly disappears midway through a set.
= if you go to Preferences > Controllers is your mouse listed there, if so is it also enabled?
If yes, disable it and check if the pointer persists.