zSlider | pure JavaScript Carousel/Slider plugin | Carousel library

I'm trying the create a 3D subscene with objects being labelled using Label objects in a 2D overlay. I've seen similar questions to mine on this subject, and they all point to using the Node.localToScene method on the node to be labelled in the 3D space. But this doesn't seem to work for my case. I've taken example code from the FXyz FloatingLabels example here:

FloatingLabels.java

The Label objects need to have their positions updated as the 3D scene in modified, which I've done but when I print out the coordinates returned by the Node.localToScene method, they're much too large to be within the application scene, and so the labels are never visible in the scene. I've written an example program that illustrates the issue, set up very similarly to the FXyz sample code but I've created an extra SubScene object to hold the 2D and 3D SubScene objects in order to plant them into a larger application window with slider controls. The 3D scene uses a perspective camera and shows a large sphere with coloured spheres along the x/y/z axes, and some extra little nubs on the surface for reference: