[2021] Windows taskbar

Check in Options to make sure the game isn't in Windowed mode.

It's also possible it isn't related to the game. Check if other full screen programs hide the task bar like they should.

Originally posted by Belhade: This occasionally happens to me, it's not the windowed setting. Don't know what exactly, but rebooting the computer fixed it.

Next time it happens, try going to the task manager and find the Windows process called "explorer" and restart it. That should do the trick and will save you the reboot.