Remove "Start Scanning" button and scan automatically.
As per the HIG, apps should try to reduce user effort. Specifically:
If something can be done automatically, do it automatically.
Pertaining to the devices view - to me, the "Start Scanning" button seems redundant. If the user is in that view, they'd likely want to scan anyways, and it would be better to do that automatically. I don't think it is a particularly expensive operation, and in Settings the Wi-Fi and Bluetooth panels already do this.