Unable to change colors for object - Illustrator on Windows

Recently, I’ve had a problem where I can’t change an object or stroke’s colors. When I open the swatches and select a new color, it highlights the new swatch while my mouse clicker is depressed, then immediately hops back to the old one. 

The color change is reflected in the “color picker” box on the sidebar, but not in the Fill/Stroke swatches panel  in the top toolbar. The object does not change colors.

I created a new file and tried it there and had the same problem. I checked the appearance panel and determined that I didn’t have any additional fills or strokes in place.

I updated AI to 30.1 (or whatever the most recent edition is). The problem resolved itself briefly, but started again after about half an hour of work. 

I tried switching the document color mode to RGB and back.

Please help! Video documentation attached.