Xara :: PDF Export Displaying Ellipse / Shape Boundaries?

In addition to my continual problems with getting the color output to match simulated print colors of CMYK on screen and .png printouts, I now find that upon PDF export, you can see the boundaries of an ellipse and a shape. I wanted to create a corona-style effect around the sun, so I used an ellipse and a shape, both with transparencies applied. (Edit to add: this is a design for a card deck.)

When I print the PDF export, (see the "PDF boundaries" image), the colors look way off and you can clearly see the circular boundaries of the ellipse and/or shape; it will do it on either one. All that should be visible is the white "corona" around the sun, which is subtle and indicated by the blue arrow pointing to it on the image "Sunrays."

Having discovered this problem, I've experimented with all sorts of variations of trying to get that corona, including the "glow" effect, but don't know how to change the color of the glow, itself. But it shouldn't be printing those boundaries to begin with, so something is off somewhere.

I'm exporting with PDF/X-3, 300 dpi, Limit bitmap resolution to rasterization resolution, JPEG quality at 100, exclude invisible layers.