disables auto lock timer on my phone

This is a pretty good app- EXCEPT- it wont let my phone auto lock once the app is open/playing. It just dims the screen but it still stays on allowing anyone in the night to access your phone. I have to manually lock the phone to secure it at night which I sometimes forget. I have turned on lock screen in settings and nothing seems to work. This is a big concern for me hence the 3 star rating. If they can get this working then it would be 5 stars. I have emailed support so lets see what they suggest. This app needs to be fixed!!!

AAA546 about White Noise, v6.1.2