Did you use the instructions shown here?: https://www.rustlevels.com/XPerience/index.php/setup/image-urls
first, check to make sure there are no images in the image folder that say 0kb in size.
if any appear as 0kb, delete that image and reload XPerience, it will redownload that image.
then unload ImageLibrary and go to your /oxide/data/ImageLibrary/ folder and delete all 3 data files. Then reload ImageLibrary so that it can reset it's data cache. When reloaded it will show download progress for ImageLibrary. After that is completed reload XPerince