That looks like a bug in Acrobat's conversion. If the circle is opaque and on top of the rays then the flattening should work better than that. The flattening process that Designer Pro uses when exporting PDF/X isn't currently as advanced as that done by Acrobat/Illustrator as when we implemented a similar system it also produced various similar ghosting effects. It is hoped that we can revisit this in the future to generate better results though this still won't necessarily avoid all issues when using transparent objects.

Gerry