I would say that neither the edge curve, nor the curve from copying the edge curve, are being recognized as a circular arc.

A new arc draw over top of the edge is recognized as a curcular arc, and the dim arc works fine.

Cannot remember all of the new curve methods...is a line, is an arc (?), is open, is closed, etc... to see how the curve is ID'd.
How does MoI know if a curve is an arc?

- Brian