Hello tomas -
we are not aware of any issues on our end that would prevent a gallery image from being created by eBay or displaying on eBay. Typically, if the header/gallery image you submitted with a listing is showing up in the header image area and not the gallery image area (such as search results), it is indicative that eBay was unable to make a copy of the image for display in the gallery for some reason. You should be able to correct this problem in any listings that are affected using the eBay tool, here.
This is an eBay tool that should prompt the service to try making another gallery image for your listing. If you encounter difficulty with the tool, please contact eBay for assistance. If this difficulty persists for you with other listings, please feel free to file a support case from under the Help tab of our site, providing a few examples of listings where this occurs so we can look into it further.