Mouse cursor frequently disappears
I have this problem sometimes with 10.14.6.  I can fix it by moving the mouse to one of my hot corners (e.g. start screensaver) or by clicking on one of the top menu items.  Basically I move it all the way to an edge of the screen even though I can't see it, and then trigger a response.
It's still pretty aggravating, but at least I can get back on my way pretty fast.