Hi @HansSp,
The PDF reader that’s included in OJS is the PDF.js viewer, which is a third-party tool available here: PDF.js
If it’s not rendering a PDF correctly, you’ll need to raise the issue with that project.
It’s possible that OJS currently includes an older version of the plugin than is currently available; in that case, updating PDF.js to the latest should resolve the issue.
I would suggest testing your PDF with PDF.js outside of OJS to see how it renders.
Alternately, you may be able to tinker with your PDF generation settings in whatever tool you’re using to generate PDFs; this may result in a file that PDF.js can reliably render.
Regards,
Alec Smecher
Public Knowledge Project Team