The most common cause of gallery images not loading is because an image file contains invalid characters. To learn about what characters are accepted for image files, please read What characters are allowed in my image names?
If your file name is valid, there may be invalid characters in your IPTC data. Open your image in a program such as Lightroom, Photoshop, or Aperture and confirm that your IPTC data doesn’t contain any garbage data.
If you need more help figuring out why your image won’t load, please contact Redframe Support.