Welcome to the Community! :smileyhappy:
I found the problem, another user had posted he had a magnetic case (like rokform) part of screen where magnet is located was the dead spot. I replaced the magnet with a golf ball marker from golf divot tool (exact same size) and now screen works fine and phone still sticks to rockform magnet on dash.
If your using the rockform case with magnet inside. I popped out the magnet and used a golf ball marker, (they're the same size) & they're steel and phone still sticks to rockform magnet. Phone works normal now.
I have same problem on my Note9 and do not have any magnetic case. There is a distinct void of ~2 cm laterally across entire screen, just below the middle of the screen. The S Pen works above and below it but seems to be disabled going across this area.
I've run the S Pen diagnostics and it fails on those squares in that same 'band'. If I draw long and vertically I will see the line up to that band and then even moments past the band. If I circle atop the band its like the 'ink' comes back on an old roller pen, so I can draw back across the void just after the band it will indeed draw in that space again.
I have gone so far as to scribble the entire screen to confirm there are no other dead spots. Just that band. Furthermore, on the right of center of the band, when I draw laterally, the line bumps upwards from the point of the S Pen, like it was going around an object.
Thoughts from Samsung?