Hello Michael,
Unfortunately there are some known issues currently at eBay with the image service which we are awaiting resolution on to be able to look into this further. Essentially, the issue is that when you submit your images with your listing using a third part service, such as ours, they are submit via the API, which allows more self hosted images than when you post directly on eBay. When you go to revise directly on eBay, this causes the issue you've run into.
We suggest that you make as many revisions using the tools available on the Active Listings page of your Auctiva account as possible and if you find that there is a revision you cannot make from there, please let us know so we can look into building an appropriate tool for it.
- Craig