AnchorAnimations ignore everything but the default values

import QtQuick 2.0

Item {
    id: root
    width: 400
    height: 400

    Rectangle {
        id: rect
        width: 50
        height: 50
        color: "red"
        anchors.left: parent.left
    }

    Timer {
        running: true
        interval: 4000
        repeat: true
        onTriggered: {
            if( root.state == "" )
                root.state = "right";
            else
                root.state = "";
        }
    }

    states: [
        State {
            name: "right"
            AnchorChanges {
                target: rect
                anchors.left: undefined
                anchors.right: root.right
            }
        }
    ]

    transitions: [
        Transition {
            to: "right"
            reversible: true
            AnchorAnimation { duration: 3000 ; easing.type: Easing.InElastic}
        }
    ]
}