OneNote's box-outlines and text caret randomly become unresponsive on Sierra and High Sierra When you hover your mouse over a "box" in OneNote, it should look like this:



Instead, randomly, the application stops responding with the box outlines (my mouse is in the same place both above and below, i.e. where the caret is):



The box outlines don't matter that much, actually. It's the fact that the caret disappears, so you have no visual cue as to where you're typing, and also that when you Backspace, you start deleting from some other place (the previous line, I think).

No amount of clicking anywhere else in the application (menus, other notebooks) or clicking out and back fixes the problem. It's really frustrating!

Is there a workaround?
I found a consistent workaround for myself:

Three-finger-swipe up (or any equivalent, to see your Spaces), select any other application, and OneNote should be normal again when you come back.

This issue may (or may not) be occurring due to using multiple desktops (Spaces), and possibly due to having multiple OneNote windows open (on different desktops).