This is one of the few places where this problem is even mentioned but it was with a insider preview 14905 way back in 2016. Just about every Windows 10 install that I have has this problem. I should say just the ones that were a "free" upgrade. Fresh installs seem to be OK.

Anyway..... when you click on the power button withing the start menu it closes so fast you can't click on "Start", "Shutdown" or "Restart". In my case it was interjected in 1703 and not fixed in 1709. Has anyone recently come across this issue and/or know of a fix?