I also have issues connecting my bitdo N30 pro to my raspberry pi 4B. I managed to connect it via internal as well as via external Bluetooth dongle. I can map the buttons and in the batocera menu everything works fine, but as soon as I join a game , like Mario kart on Nintendo 64, 90% of the pad buttons are not assigned anymore and the controller looses connection. When plugged in via USB cable, the controller works fine. Any advice ?