Hello!
I just checked a dozen of your listings on eBay and they are all showing the scrolling gallery. Is there a particular listing that you are having the issue with? That might help narrow down the problem.
Another thing to try is to clear your browser's history, reboot and see if that does the trick.
You may need to file a support ticket if you continue to notice any problems. Like I said, I could see the gallery fine in both Internet explorer and Firefox browsers, so chances are that your customers are seeing it ok too.