Hi, I have got the same problem - no gallery pics. Received a reply from Auctiva:-
"Thanks for contacting us regarding this matter, and I’m sorry to hear about the trouble you are having. I would like to assure you that currently there is nothing wrong at our end which would account for this issue. However, we have been receiving similar type of cases from other users. Since, there is nothing awry at our end currently; this issue must have arisen due to some temporary communication failure between eBay servers and Auctiva. In order to rectify this problem, I would request you to refresh the images for those specific listings that are exhibiting this problem. Please find the instructions for the same as provided below:
1) Visit the item on eBay.
2) Right-click the image you’d like to make your new header/gallery image and click “Properties”
3) Copy the image URL, which begins with http://...
4) Click the “Revise your Item” link at the top of the auction page.
5) Click the “Add Pictures” button.
6) Delete the text (if any) in the “Enter URL…” field (if any) and replace it with the copied URL.
7) Click the “Insert Pictures” button and save your changes"
It didn't work for me, but maybe it will for you??