Line Chart Series Renderer ignores 'type'

I'm attempting to change the "node" on a line chart based on record values. I am able to change the color and size, but it seems 'type' is ignored.

Code:

renderer: function(sprite, record, attr, index, chartStore) {
  if (record.get('status') == 'open') {
      Ext.apply(attr, {
          type: 'image',
          src: 'images/open_data_marker.png',
          fill: '#FF3333',
          width: 32,
          height: 32
      });
  }
  return attr;
}

I'm using 4.2.1, if that matters. I've also attempted drawing the image in the renderer and attaching it to sprite.surface, but that doesn't seem to work either.



Line Chart Series Renderer ignores 'type'