AutoCAD 2014 'Tangent' ignores ellipses in isometric, but ...

In isometric, AC14 won't run a tangent from one ellipse to another - well not at first try anyway.

I have discovered that if you do a dry run starting a line from a point and continuing it successively tangential to the ellipses the lines will appear but the second won't be tangential. It you erase those lines and go Line --> Tangent --> select first ellipse --> Tangent --> select second ellipse then Tangent works fine.

Is that a bug, or a feature?