Post your issue in the eBay.com Photos &HTML forum. This issue has appeared there in the past weeks. Post your browser name and version as well as you computer operating system.
One cause is if you use Internet Explorer on Windows 7 and upgraded to Internet Explorer 10. If you use compatibility mode in Internet Explorer it might help.
You may want to try FireFox. The latest version is 21.0.0 but I have read it is causing issues. I currently use FireFox 20.0.1 with no issues. I have FireFox option setting to not upgrade FireFox automatically, to just inform me that an new version exists. I always wait for for the latest version to be out for a few weeks before I upgrade.
If you use the latest version of FireFox, it allows you use the new picture uploader. I find the new picture uploader to work well.