Why Some Areas are not Recognized by S Pen Action in Samsung Galaxy Note8?
Firstly, please check your 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 may not work properly.
Also, if you use the S Pen at sharp angles on specific areas affected from magnetic force like around Front Camera, S Pen may not work due to magnetic force. At that time we recommend to put your S Pen upright and use the S Pen with more force. Additionally, if you use the S Pen at sharp angles anywhere on the screen, The device may not recognize the S Pen actions.