The S Pen assists you in performing various functions. Samsung Galaxy Note 9 S Pen does not work well for previewing content, take a photo or entering text could be due to connection problems between the S Pen and the phone. You can try the reset function to reset the connection.
- Insert the S Pen in the S Pen slot.
- Tap Settings app or swipe down from the top and tap that little gear on the top right.
- Tap Advanced features → S Pen → S Pen remote.
- Tap More Options (three dots in the top right) → Reset S Pen.
The above method does not work? You can do a factory reset and don't forget to back up relevant data before doing so.