We just received an update on this issue from eBay's Developer Support team and they have assured us that this should no longer happen with new listings posted after this point. However, unfortunately, they also informed us that they likely will not be able to do anything to create these missing gallery images in bulk.
However, I have heard comments from a few users who have contacted eBay about this suggestion that eBay's technical team is working on the problem, so perhaps they will be able to come up with a method to fix these images in bulk based on reports from users.
If you have a relatively small numbers of listings that are missing gallery images, you should be able to correct the problem in those listings fairly easily using the eBay tool that can be accessed using the following link: http://cgi5.ebay.com/ws1/eBayI...ayGalleryImagePageV3
If you have a large number of missing gallery images and it is not feasible to fix them using this tool, I recommend contacting eBay's customer support team to see if they have any more efficient solutions that can be used on a case by case basis.
I will keep you all posted if I receive any new information about this situation.