signal dataChanged does not update the QML ListView

Example is in attachment

1) program a QAbstractListModel with a slot or Q_INVOKABLE that changes it's data and emits a dataChanged similar to this:

void Model::changeData()
{
m_elements[1] ="x";
emit dataChanged(index(1,0), index(1,0));
}

2) extend the QAbstracListModel as a useable model in QML as is done in the example

3) hook up the model to the listview and the slot to a key press.

===>The slot gets called, the method QAbstracListModel::data() gets called, but the listview does not get updated

Notes: a model reset() will update the listview.