Android startBluetoothSco not starting sco but isBluetoothScoOn returns true
There are many things missing in the Android documentation, however, if you call startBluetoothSco() and stopBluetoothSco() each time during audio routing there should be no problem routing the audio properly.Even I have seen when the connection is kept idle for long and we start StartBluetoothSco() we directly get disconnection.To solve this I wrote a workaround which is here: https://github.com/kodered/Bluetooth-Refresh-Logic
Hope this helps.