RE: MX Master 3 / Options+
FYI, I just tried setting the Middle Button to do a Screen Capture, but it would not work. I was going to uninstall the Options+ software and then reinstall it. But, I discovered that the old LogiOptions was still installed. I thought the install of Options+ would have uninstalled the old stuff - but it did not.

Anyway, I uninstalled the old LogiOptions software and the Screen Capture on the Middle Button began to work!

I just thought I'd pass this info on to you.