Not sure if anyone has tried this yet, but when you turn on the isometric grid, it defaults to the left plane. There is no toggle between planes, like a CTRL+E. You can type in isometricgrid and then select top, left, and right. The real problem is when you use the isocircle option of the ellipse command, the isocircle stays in the left plane. The help said that you can use F5 to change the isometric grid, but nothing happens.