I'm sorry to hear about the difficulties you have been experiencing lately. Assuming that there is nothing wrong with the images you selected for display in the Gallery, it is most likely that eBay's system encountered an error when attempting to make copies from the Auctiva hosted images that were sent to them for that purpose.
Unfortunately, this has been known to happen at times and there is not anything that we can do differently from our side of things to to prevent eBay's system from encountering errors of this nature on occasion.
I am under the impression that eBay will typically attempt to generate the Gallery image again automatically if their first attempt to do so fails, but the Gallery images can also be restored by revising each listing manually as you mentioned you have been doing.
Although you can restore the Gallery images in listings which have been impacted in this manner by uploading a new copy of the image through the Revise your Item form, eBay also offers a “Fix your Picture” tool that is intended for this purpose which you can reach using the following link:http://cgi5.ebay.com/ws1/eBayI...ayGalleryImagePageV3
If you need any further assistance with your account, please feel free to contact our Customer Support team by mousing over the “Help” tab within your account and selecting the “File Support Case” option.