we are facing a freeze problem with some customer PPTX files.
The Apose.Slides version we use is latest v19.6.0. The problem occurs with both demo and licensed version.
I created and uploaded a small repro project to https://drive.google.com/open?id=1qiq8I4T--d6gxTMZpODrtzSjbmIss7VK
When running the Debug build, it will try to convert the slide to an image when you click on Convert!.
An affected PPTX file is located under bin\Debug.
The application will hang indefinitely in the call to IAsposeSlide.GetThumbnail().
Please let me know if you need any further information.
I have worked with the sample code and presentation file shared by you and have been able to observe the issue specified. An issue with ID SLIDESNET-41256 has been created in our issue tracking system to further investigate and resolve the issue. This thread has been linked with the issue so that you may be notified once the issue will be fixed.