Почему не работает position.direction для PositionSource?

QT += quick positioning

import QtPositioning 5.4
...
    Text {
        id: labelLongitude

        anchors.left: parent.left
        anchors.top: parent.top

        font.family: "Helvetica"
        font.pointSize: 24
    }

    Text {
        id: labelLatitude

        anchors.left: parent.left
        anchors.top: labelLongitude.bottom

        font.family: "Helvetica"
        font.pointSize: 24
    }

    Text {
        id: labelSpeed

        anchors.left: parent.left
        anchors.top: labelLatitude.bottom

        font.family: "Helvetica"
        font.pointSize: 24
    }

    Text {
        id: labelDirection

        anchors.left: parent.left
        anchors.top: labelSpeed.bottom

        font.family: "Helvetica"
        font.pointSize: 24
    }

    Text {
        id: labelMagneticVariation

        anchors.left: parent.left
        anchors.top: labelDirection.bottom

        font.family: "Helvetica"
        font.pointSize: 24
    }

    PositionSource {
        id: positionSource
        updateInterval: 1000
        active: true

        onPositionChanged: {
            var coord = positionSource.position.coordinate;
            console.log("Coordinate:", coord.longitude, coord.latitude);

            labelLongitude.text=qsTr("Longitude: ")+(coord.longitude);
            labelLatitude.text=qsTr("Longitude: ")+(coord.latitude);

            labelSpeed.text=qsTr("Speed: ")+positionSource.position.speed;
            labelDirection.text=qsTr("Direction: ")+positionSource.position.direction;
            labelMagneticVariation.text=qsTr("Magnetic Variation: ")+positionSource.position.magneticVariation;
        }
    }