Drag in MouseArea failing if drag.target is not set

// main.qml
import QtQuick 2.8
import QtQuick.Window 2.2
 
Window {
    width: 360
    height: 360
    visible: true
 
    MouseArea {
        id: ma
        anchors.fill: parent
 
        //Item { id: dummy }
        //drag.target: dummy
 
        drag.target: ma // needs a target! dummy target works too
 
        onClicked: console.log("ma clicked")
 
        Rectangle {
            color: ma.pressed ? "red" : "yellow"
            width: parent.width / 2
            height: parent.height / 2
            anchors.centerIn: parent
 
            Text {
                text: "MouseArea::pressed: " + ma.pressed
                    + "\nDrag.active: " + parent.Drag.active
                anchors.centerIn: parent
            }
 
            Drag.active: ma.drag.active
            Drag.dragType: Drag.Automatic
 
            Drag.onActiveChanged: console.log("active", active)
            Drag.onDragStarted: {
                console.log("rect drag started", Drag.imageSource)
            }
            Drag.onDragFinished: console.log("rect drag finished")
        }
    }
}