Screen never sleeps even when the app is not running

[slabua]

As long as the app is connected to a device, even when not in foreground, the phone screen never turns off.
Selecting None (disable) makes the screen go off normally after the phone settings timeout.

[slabua]

After some testing, the reason why the screen did not turn off even when the app was in background, but still connected to a device, was due to the fact that the Range test module was active, and the devices kept pushing the ping messages in intervals which were shorter than the display timeout itself.