As noted, if your Header image, the main image in the upper left of an eBay listing is showing on eBay, they have received the data we sent with your listing and have run into difficulty making a copy of the image for use with the gallery. We provide the image as indicated in your Saved listing when you submit it and eBay makes copies for use in the locations on eBay where it is displayed. We have no control over what occurs once eBay has received the data provided from your Saved listings.
If you are having difficulty with the images that appear in the body of your listings, please file a support case with some example item numbers so our support team can have a look into it, as that would indicate a different issue.
Please also note that if you have run into difficulty with the tool that eBay provides to recreate the gallery images when there are issues with that image being created, you will need to contact eBay directly.