I went through the tutorial and then was working on the practice cubes, and part way through number six it stopped updating the 3D. I reloaded tab and then there as no 3d colour stuff in the 3D view at all, only the wire-frame cube and the cross sectional 2D plane. Tried clearing cache, cookies, restarting browser and still not seeing the 3d neuron there.
We were actually having an issue with the 3D images but that should be fixed and back up today or tomorrow. Sorry for the inconvenience there!