In my case, I think the palm rejection works just fine both in S note and sketch pro (and in other s-pen apps recommended by samsung). Just try and test it this way: set the "air view" on, and when the display captures the hovering point of your s-pen then the palm rejection works. So when you draw you shouldn't pull away the pen too far from the display (the hovering point must be detected) and you can move your palm freely on the display without being registered as drawing movement or pan/zoom gesture.