For me the problem was Nvidia GEForce Experience's "In-Game Overlay". What actually is happening is that when this is turned on, the taskbar is behind the window, and if it is maximized, well, it is behind it entirely. You can restore the window to unmaximized and move it so that that it covers the taskbar, the task bar should be on top, but it is behind the window. You turn off "In-Game Overlay" and viola, the taskbar is on top again. This was a real tricky one because we always blame Microsoft
In GEForce Experience, click Settings, you'll get this screen.
