Check your device drivers, particularly your mouse/touch pad drivers. This is precisely the issue I had (and continue to have) on an old Dell Inspiron 1720.
The general pattern is that the icons in the quick launch bar and system tray will respond to a single left click for a period of time, and the start menu always does, but in short order the quick launch icons stop responding and the start menu appears, but nothing on it can be activated.
In my case I have given up on finding a driver that will work as I've exhausted virtually every option. The best place to start is at the website of the manufacturer of your hardware. Even if there's not a driver specifically noted for Windows 10 the ones for Win8 often work as well.
If this is not a desktop machine I'd also suggest trying an external mouse just to see what similarities and differences you might get in behavior, and do so over a period of hours.
Brian AKA Bri the Tech Guy (website in my user profile) - Windows 10 Home, 64-Bit, Version 1803, Build 17134
Memory is a crazy woman that hoards rags and throws away food.
~ Austin O'Malley