-If you never restart your computer, do a complete restart of your computer. (Hold down shift when shutting down on Windows). See if that fixes the issue.
-Delete cookies.
-Disable add ons.
-Sign in and out of eBay.
-Try a different browser.
-Create a fresh new listing. Could it be the draft is the problem? If the new listing shows the pictures and the draft doesn't, there must be an issue on eBay's end with the draft.