Rendering problem with fading graphics

[GuernseyMan]

I have a number of books which have a gradient transparency on one edge of the each page. When I use other readers (Foxit, Adobe etc) it renders correctly:

When I use FlexiDPF 2025 (both 32bit and 64bit versions the transparency is not rendered properly, the graphic shows completely opaque:

The physical book has the fading so I'm sure that's how the PDF is supposed to render. I've attached a sample page from the book so you can see how the author has set the graphic up.