You're all glorious people! That fixed mine too (also with Lenovo Flex 3)!

That's interesting. I hadn't noticed the keyboard issue; but, I just tried pressing and holding a key and it appears to have that same issue too.

In your System Restore, were their any noticeable...

I'm having the exact same issue, slightly different PC specs, although similar. Again, no issue with the Task Manager in the foreground or while on the Security Options.

Update: With all internet...