Thanks for your inquiry. We will appreciate it if you please share your sample PDF document here, so we will look into it and will guide you accordingly.
Thanks for sharing the source document. I have tested the PDF to PDFA scenario with both 11.4.0 and 10.9.0 DLLs and noticed that both version produce incorrect results. So logged a ticket PDFNEWNET-40536 in our issue tracking system for further investigation and rectification. We will notify you as soon as it is resolved.
Thanks for your inquiry. We have good news for you, your issue has been fixed in Aspose.Pdf for .NET 11.6.0, result of some other fix. Please download and try latest version of Aspose.Pdf for .NET, it will resolve the issue.
Please feel free to contact us for any further assistance