Sometimes the firewall pop up window does not display. I can hear the Windows sound if it activating but cannot see the window, not even using alt tab.
The issue persists until I restart the PC. I've attached a screenshot of the missing window.
It's hard to reproduce since it is random and I need to restart after it happens. If I'm not at the PC when it happens, I don't know it happened since there is no visual que, only the Windows sound.