I have it working on Windows (The two com ports are: one for outgoing connection - which we need to use, and the other for incoming, which can be deleted, as not required). Its Android I have the issue on. I am able to configure the BT connection in Android settings (pair it, enter the PIN etc) and this BT connection works for the Tower app just fine. But in QGC, I can add the bluetooth connection, scan and see the device and choose it, then click connect, and all appears OK until I go to the main screen and see the error saying it failed to connect. I presume it uses the connection/pairing details stored in Android settings as the QGC connection does not prompt for a BT device pin etc.