You keep mentioning Dawn with Synthrapol, and I'm not sure what you mean. As far as I know, no version of Dawn contains Synthrapol. Some people claim to get good results with Dawn, but I have not seen any real tests with known bleeders that showed its effectiveness for quilting fabric or that scientifically explained why it works.
I think that it is possible sometimes to see the top fabric's shadow on the quilt back, if the quilt is wet and the batting is not very thick. Perhaps that's what you saw? If so, the shadows will disappear when the quilt dries.