MultiEffect (shadow) not working as expected

Rectangle {
    id: rect
    property int rectHeight: 100
    property int rectWidth: 100
    property int rectRadius: 10
    property int shadowSize: 10
    x: 100
    y: 100
    height: rectHeight
    width: rectWidth
    radius: rectRadius
    color: 'lightblue'
}

MultiEffect {
    source: rect
    anchors.fill: rect
    autoPaddingEnabled: false
    paddingRect: Qt.rect(0, rect.rectRadius * (-1), rect.rectWidth, rect.rectHeight)
    shadowBlur: 1.0
    shadowColor: 'black'
    shadowEnabled: true
    shadowVerticalOffset: rect.shadowSize
}