In Ensemble on the 3D Cubes sample, the text on the tabs doesn't show up. This is because it has a drop shadow effect applied to it. If you add:

#root .tab *.tab-label Text {
    -fx-fill: red;
    -fx-effect: null;
}

to ensemble2.css then that will turn off the effect. Also it changes the text color to red so its easy to spot that this is taking effect. After this change the text shows up fine. I expect this is a graphics bug.