I also have had this issue appear repeatedly over the past few months. I am currently working off a laptop with a second monitor connected. When dragging the microsoft word window to the second monitor i notice the cursor disappears
over the italic text, however, when i drag the window back to my laptop monitor, the issue is no longer present.
My laptop screen resolution is 3840x2160 while the external monitor is 1920x1080.
I also notice that by restarting all microsoft office programs the issue temporarily disappears. Hopefully this information helps find a solution to this problem which appears to date back to 2013.
edit: typo