Weird effect on MultiEffect and NumberAnimation

Item {
    id: item

    MultiEffect {
        anchors.fill: item
        source: item
        shadowEnabled: true
        shadowColor: "#9B9B9B"
        shadowBlur: 1.0
        shadowHorizontalOffset: 8
        shadowVerticalOffset: 8
    }

    ProgressBar {
        background: Rectangle {
        }
        contentItem: Item {
             Rectangle {
             }
        }

        NumberAnimation on value {
            running: item.visible
            from: 0.0
            to: 1.0
            duration: dismissTimeout
            onFinished: {
            }
        } // NumberAnimation 
    }
}