I had to turn WindowFX (6.13) off. It was causing the task bar on my secondary monitor to disappear. When I turned it off, the taskbar came back. Running Windows 10.
Update: It happened again with WindowFX off, so it wasn't the problem. The taskbar search field starts blinking and then the task bar goes away. Anyone else seeing this? (only on my second monitor. The primary monitor retains the taskbar).