I included the GalleryURL and set the GalleryType to Gallery in my AddItem request, but instead of seeing my Gallery Image on the site, I see the following:
Why is this happening and what can I do about it?
You need to check the following by making a call to GetItem for the ItemID:
The GalleryType is not None
The GalleryURL is correct and that the image renders correctly
The Color Model of the image is RGB and not CMYK
If you host the images on your servers, after the item is added, the gallery image is retrieved from your server and stored on eBay Picture Servers. It is possible that when eBay tried to retrieve the image from your server, there may have been a momentary lapse in network connectivity and the image could not be retrieved. In this situation, if you make a call to ReviseItem by setting the entire PictureDetails container again, the issue is most likely to be resolved. If you are using the deprecated containers, VendorHostedPicture or SiteHostedPicture, it is strongly recommended that you stop using the deprecated containers and use PictureDetails instead.
Consider uploading the images to eBay by using UploadSiteHostedPictures. This will ensure that the gallery images are always available at the time of listing your items.
If you decide to host the images on your website, ensure that they are available within 5 secs, otherwise eBay servers will timeout and fail to create the gallery images. Also, avoid redirection to another webpage.
Ensure that the images and the URLs are in one of the supported formats such as jpeg, bmp, tif or gif. If your URLs do not end in one of these extensions, the behavior will be unpredictable.