I found issues on testing Aspose CAD for .NET 18.3.0.0
When I converted some dwg/dxf files to PDF with your ExportToPDF sample, Adobe Reader shows a warning message like this;
An error exists on this page. Acrobat may not display the page correctly. Please contact the person who created the PDF document to correct the problem.
Some contents are not displayed at Adobe Reader. However, they are displayed well at other PDF viewers like Google Chrome.
Though I have many PDF files which make the issue, I cannot send to you because of security issue (NDA).
Instead, I found an open dxf file which makes same issue.
I have observed the information shared by you and have tried opening the PDF files on my end in Adobe PDF viewer. There is no issue observed while opening the specified PDF on my end in shared version. Can you please share the used sample code along with PDF viewer version used on your end and snapshot of issue. I will investigate the issue further on my end to help you.
I have observed the issues shared by you and have been able to reproduce that on my end. An issue with ID CADNET-578 has been created in our issue tracking system to further investigate and resolve the issue. This thread has been linked with the issue so that you may be automatically notified once the issue will be fixed.