Who I have the same questioned this topic

After I updated to the 6.01 version, my proximity sensor began to act up. When I am in a call and put the phone to my ear, the screen turns off as expected. But, when I pull the phone away, the screen stays off. It has never acted like that. I did a factory reset, but no change.

Others have reported this problem on the Google forums, but I wanted to see if other Verizon Note 4 users were having this issue. I'm not sure if the sensor is bad, or if it's a bug in Marshmallow. It didn't do this before the update, so it's hard to imagine it's a bad sensor.

I would appreciate any feedback or help if you have a way to fix it. I tried an app from the Play Store to test the sensor. It shows that once the sensor sees something "near", it stays in that state even if you pull your hand away. It is supposed to go back to "far" when you pull away. Thanks!