Bluetooth headphones can be used by changing the "Disable USB audio routing" setting in the developer options.
Refer to the following guide Configure on-device developer options | Android Studio | Android Developers to enable developer options on the Motorola Edge device.
- Open Settings > System > Developer options then scroll down far to Disable USB audio routing and enable it. (The setting can also be found via serarch)
- Restart your phone to make sure it takes effect.
- Connect the phone to your Bluetooth headphones. They can be used as usual now.