This 'workaround' tip may be useful if you need to draw tangents between ellipses or you need to draw a cone for example.
1.First draw your ellipse or 'project' your circle to an Isometric view by using the Isometric Projection tool (PJ). Then select and explode the ellipses -via main menu > modify > Explode (XP), this will 'break' down the ellipses into separate arcs.
2.Tangents between ellipses - once the ellipses have been exploded,use the Tangent tool (CC - circle to circle) and place the cursor close to or on the arc - select and then do the same for the other ellipse.
3.Cone - use the Tangent tool (PC - from coordinate point to an existing arc,circle or an ellipse). repeat the process!