When I tried to transform the PPT file (attached) to PDF, underline is replaced with a strikethrough.
Thank you for your interest in Aspose.Slides.
I have observed your comments and worked with the presentation file shared by you. I am unable to reproduce the issue on my end. I have attached the generated output file for your kind reference. I request you to please try using Aspose.Slides for .NET 15.8.0 on your end and then share your kind feedback with us.
Please let us know if the issue persists. We will be happy to assist you further.