I’ve had this problem por almost 6 months. Most of this time I thought it was a Windows 10 issue and I waited for this long in the hope updates would fix it. A couple of days ago I decided to spend all day until I solved the problem or either format. When I booted in safe mode, all taskbar buttons and functions worked. This led me to narrow down the problem by disabling services at startup. I narrowed it down to Comodo Firewall (Version 10, I’m not a fan of constant updates).
I was amazed on how a firewall program could have this behaviour. Seriously, how on earth programmers make a firewall to block taskbar functions in Windows 10? Firewalls are supposed to block traffic, not how an OS works.
I’ve installed Comodo Firewall 11. It works fine for now, but if I end up having the same behaviour again, I’ll have to uninstall it for good, and of course, stop installing it in my clients computers.