ListView - contentY goes crazy

import QtQuick 2.7
import QtQuick.Controls 1.5
import QtQuick.Dialogs 1.2

ApplicationWindow {
  visible: true
  width: 640
  height: 480

  ListView {
    id: listView
    anchors.fill: parent
    model: testModel

    delegate: Text {
      id: delegateItem
      width: listView.width
      height: 40
      horizontalAlignment: Text.AlignHCenter
      verticalAlignment: Text.AlignVCenter
      text: name_role

      Repeater {
        model: 10
        delegate: Image {
          source: "qrc:///test.png"
          cache: false
          visible: false
        }
      }
    }
  }

  Button {
    id: button
    anchors.right: parent.right
    anchors.bottom: parent.bottom
    anchors.margins: 10
    text: "test bug"
    onClicked: {
      testModel.modifyName(40, "asdasdads")
      testModel.removeRow(30)
    }
  }
}