We have another file (see attached) which cause PDF/A-1b validation errors using Preflight after PDF to PDF/A conversion.
Thanks for your inquiry. I have tested your scenario with shared document using Aspose.Pdf for .NET 11.1.0 and managed to observe compliance issue. For further investigation, I have logged an issue in our issue tracking system as PDFNEWNET-40140 and also linked your request to it. We will keep you updated via this thread regarding the issue status.
We are sorry for the inconvenience caused.