[Regression] ListView isn't draggable with ListView.OverlayHeader

import QtQuick 2.12
import QtQuick.Window 2.12

Window {
  width: 640
  height: 480
  visible: true
  title: qsTr("Hello World")

  ListView {
    anchors.fill: parent

    headerPositioning: ListView.OverlayHeader // removing this line makes the ListView draggable/flickable again

    model: 20
    delegate: Rectangle {
      width: parent.width; height: 100
      color: index % 2 ? "blue" : "grey"

      MouseArea {
        anchors.fill: parent // MouseArea fills the whole delegate
      }
    }

    header: Rectangle {
      color: "red"
      width: parent.width; height: 100
      z: 100
    }
  }
}