LG G4 :: Power Button And Proximity Sensor

I have an LG G4 since December 2015 and like many people I found out that "Double tap" to wake the device does not always work.So, I ditched this feature and used only the power button to wake the device.The problem is that even the power button does not always wake the device, many times, a second push being needed to successfully wake the phone.I even called LG support and scheduled a visit to the service center.

Today I think I found the reason why the power button does not always work, at least for my device.I usually leave my G4 with the front facing down, on the desk.When I hear a notification alert or the phone rings, I grab the phone and press the power button while it is still facing down on the desk. Many times in this situation the phone will not wake up.So I started thinking it has something to do with the proximity sensor.To test this, I covered the whole top of the phone (front side) with my palm and pressed the power button. No matter how many times I would press it, the phone will not wake up. At this moment, I will start distancing my palm from the phone while pressing the button every second.Only after the palm is at a considerable distance from the proximity sensor would the phone wake up.I thought about a feature in Android "prevent accidental wake up" but Marshmellow does not have this feature or I could not find it in Settings.

I tried searching the web for other G4 users having the same problem, but found none. Found a couple of posts about the button being defective and a couple of posts about screen protector causing the screen to not wake up after a call or interfering with taps on screen.

So the question is: It is normal for the phone to NOT wake up using the power button if the proximity sensors detects something close to the phone, like the surface of the desk?I could understand "Double tap" not working while proximity sensor detects something and that is why I am not using that feature anymore, but power button?It is working as intended? It is only my device?