Knockout Detail not showing in PDF

[xmrslx]

Hi All,

I use knockout group a lot in my work. It all worked fine but lately when sending PDF's to clients the white 'knockout' no longer appears so is effectively deleted for example showing a plain moon rather then detail within it. Is there a quick fix to this? I'm not entirely sure why it stopped working. 

Many thanks in advance.

[Ton Frederiks]

Do they use Acrobat to preview the file? Apple's Preview (and possibly other viewers) don't show knockout groups correctly.

[xmrslx]

Thanks for your reply. Likely not but they complain they can't see the detail and think I have sent dodgy files. I have started to explain that third party PDF viewers do not support transparency but I was wondering if there was a quick fix to save the back and forth emails. 

[Ton Frederiks]

You could send them a flattened pdfx file that does not support transparency.