When I use the 'btscanner example', it is impossible to make a pair with the remove smartphone. The utility always prints out an error:

qt.bluetooth.bluez: Failed to create pairing "org.bluez.Error.AuthenticationFailed"

and I do not see any notification aboout of PIN code and so on.. Also, the signals:

void     pairingDisplayConfirmation(const QBluetoothAddress &address, QString pin)
void     pairingDisplayPinCode(const QBluetoothAddress &address, QString pin)

does not triggered.

PS: But, when I use the blueman-applet, then pairing does sucessfully.