There has got to be some sort of disconnect. Maybe it is a SW thing, I let our CAD guy run that
In Illustrator, when I export as a dfx and then open in Rhino, curves are curves, not a series of straight lines, and they are joined.
In Rhino, when I save as a dfx and then re-open in Rhino, the previously joined lines and curves and unjoined, hence my Ctrl-j comment.