Try setting the confirmation first in the PAIRING_REQUEST
BluetoothDevice device = intent.getParcelableExtra("android.bluetooth.device.extra.DEVICE");
device.getClass().getMethod("setPairingConfirmation", boolean.class).invoke(device, true);
device.getClass().getMethod("cancelPairingUserInput").invoke(device);
This worked for me between two Android devices using RFCOMM but I’m not entering any PINs