Likely that nobody else is having this particular issue with the picture loader on the new advanced listing form but I thought I'd post the simple workaround I use for my issue anywho.
My problem is probably due to using an older Firefox v31, but since everything else is mostly still working I'm sticking with it for now for listing.
Up until a couple of weeks ago everything was working fine. eBay must have changed something because suddenly both the "Add Photos" buttons went completely dead (click, click, click, nothing). I haven't bothered to try to figure out what in the 1000's of lines of JavaScript went south, and likely won't bother since it's probably unrepairable.
What does work is to drag and drop the photo file(s). I have the Firefox Browser window fullscreen with the Windows Explorer window containing the photo(s) I want to upload open near the top of the screen, and drag and drop the photo(s) on to one of the "Add Photos" buttons. Works like a champ.
Everything else in the photo uploader works - rearranging and the editing features that I don't use.
If you can't get a clear shot at the buttons without drastically resizing the explorer window, you can select the files you want, and drag them over the Firefox window button on the task bar which pops the Firefox window to the top where the files can then be dropped.
