Textures seem incorrect on ellipses

[mramato]

As seen in the Visualizing Spatial Data tutorial, paste the below code into Sandcastle and you get the below image. I'm not exactly sure how a 4x4 checkerboard is supposed to work with ellipse, but it's definitely not right. Same thing for every other material I tried with ellipses (more pictures in tutorial).

var viewer = new Cesium.Viewer('cesiumContainer');

var entity = viewer.entities.add({
  position: Cesium.Cartesian3.fromDegrees(-103.0, 40.0),
  ellipse : {
    semiMinorAxis : 250000.0,
    semiMajorAxis : 400000.0,
    material : new Cesium.CheckerboardMaterialProperty({
      evenColor : Cesium.Color.WHITE,
      oddColor : Cesium.Color.BLACK,
      repeat : new Cesium.Cartesian2(4, 4)
    })
  }
});

viewer.zoomTo(viewer.entities);