Thank you for contacting and using Aspose.Diagram APIs. Please make sure that you are using the latest version of Aspose.Diagram 5.5.0. We’re gradually improving formatting issues in the each release version and recommend our clients to post each problematic Visio diagram in the Aspose.Diagram forum. If you are facing such problems while converting VSDX to PDF format, then please attach your source Visio diagram for testing purposes. We’ll investigate and reply you accordingly.