zipping a PDF removes it's contents

[studioumbrella]

I'm zipping files in multiple folders where each folder has a PDF in it.
Each folder is zipped into it's own ZIP file. After completion, the ZIP file is empty. It has the same number of pages, but they are all blank.
This is a new issue as I've been using this package for a very long time and only recently did I notice this issue.

Thanks!