Thank you for contacting support and using Aspose.Diagram API.
We have tested your sample Visio diagram against the latest version 5.8.0 of the Aspose.Diagram for Java API and managed to replicate an error message. We have logged this error under ticket id DIAGRAMJAVA-50255 in our bug tracking system. Your post has also been linked to this issue. We’ll keep you informed regarding any available updates. We’re sorry for the inconvenience caused.