Hi @Anonymous,

Are you using the "built-in" PDF or are using a another product such as Adobe Acrobat?  

It sounds like you are using the Export to PDF. Does the same thing happen when you print and Save to PDF?

If you use the latter, you can edit the Page Setup and verify that you are applying a proper CTB such as Monochrome.

With File>Export you can override the Page Setup but this might be a bit trickier.

Please attach a drawing file and I will take a look for you.

Please select the Accept as Solution button if my post fully solves your issue or answers your question.