I have observed your comments and have worked with the file shared by you. I have not been able to reproduce the issue on my end. However, a warning message as “Office has detected a problem with this file” is appearing on my side. Please report if you see the same message when you load and save the presentation on your end. I have attached the generated output presentation for your kind reference. I request you to please try using Aspose.Slides for Java 15.9.0 on your end and then share your kind feedback with us.
I have observed your comments and like to share with you that, an issue with ID SLIDESJAVA-35118 has been logged in our issue tracking system to further investigate and resolve the issue of warning message. This thread has been linked with the issue so that you may be automatically notified once the issue will be resolved.