Hi,
Please check as follows:
1. Whether the corresponding images exist in your Picture Library.
2. Is there any custom script loads in your page will affect the display of images?
3. What if you insert another Picture Library Slideshow Web Part into the same page and reference the same Picture Library, will the web part works as expected?
4. If the issue still exists, you can try to create a new page and do the test again.
Feel free to reply with the test result if the issue still exists.
Best regards
Patrick Liang
TechNet Community Support
