Dear Xara...

The Width and Height input control box labels are meaningless unless the Rotation is 0 or 180: they flip and their sense becomes Height and Width controls when the rotation is 90 or 270.
I also have no sense of which node the Rotation references: 0 seems to be due South and positive increments turn the ellipse anti-clockwise across the range 0 to 360. c.f., Lines that seem to point left and go to to 180.

Your Manual and Help totally overlook this.

Logically, the boxes should be labelled Major-axis & Minor-axis.