[Galaxy Note 8] Why it does not respond in some screen area when using the S-pen action?

Please check you attach cases or covers with magnetic material to a device.

If you attach a magnetic case or cover to the device, the device may not recognize the S Pen actions
and the S Pen is not working properly.

Also, if you use the S Pen at sharp angles on the screen, the device may not recognize the S Pen actions.