Hard to say, without being able to see the
My supposition is that you're using a PDF version (PDF 1.3? PDF x-1a?) that does not support transparencies.
Have you tried exporting as PDF 1.4?
And what does a "real" PDF viewer (like Adobe Reader) show?
(As the name says, Apple's Preview is "just" a fast preview tool)
Anyway, I don't understand why some of the scratches are still visible in the rounded rectangle.
Are they also produced by a PNG?
There are good chances that the PDF export is working in the way it's supposed to work, but some of the features you're trying to use are not compatible with the settings you have chosen.
Would it be possible for you to upload the
.svg file or a sample
.svg file that shows the issue so that we can have a try at it?