Well, cant share the file.

But, it was basically, laying down a curve. Then offsetting the curve, then I use the line tool to connect the ends to close the curve. When I used the line tool, it created corner points by default I suppose.

When I then tried to soften those hard edges created by the line tool, I realized that they must be corner points, because they where so sharp, and the fact that Fillet didnt do anything to them.