Quick example:

ScrollView {
  Loader {
    anchors.centerIn: parent
    sourceComponent: sourcecomp
  }

  Component {
    id: sourcecomp
    Image {
      width: 50
      height: 50
    }
  }
}

When trying to use a Loader within a ScrollView, this error appears and immediately crashes the program:

qml/QtQuick/Controls/ScrollView.qml:202: TypeError: Cannot assign to read-only property "progress"