I discovered the same issue and this is what I believe is happening. It is the difference between the phone responding to the S-Pen the old way and activating air command versus the new Bluetooth features of the S-Pen. When the S-Pen is close enough to the screen (so that you can see the tiny circle indicator where the tip of the S-Pen is pointing), the S-Pen acts like the old S-Pens and Notes do, so pushing the button will open air commend. When you move the S-Pen far enough away and the pointer dot is gone, the Bluetooth features will be used instead. My guess is the Bluetooth features are designed to be used when away from the phone, so why let a user use them when holding the phone? Makes about as much sense as forcing the Bixby button. So far I have not found a way to disable air command and only use the Bluetooth actions, so I just remember to pull the S-Pen away about 4-6 inches then press it.