It won’t let me upload pictures when wild releasing books. Even later on when I hit the edit button to try to add a picture, it keeps saying try again.
I was able to upload photos earlier - JPEG images. What kinds of images are yours, and how big? The site's supposed to re-size them, but if they're too large to begin with it may simply fail.
Also - I don't know if this is a factor, but in some cases the site works better if it's in secure mode. That is, if the URL is "https://www.bookcrossing.com" instead of just "http://". I know that applies to the bookplate labels; don't recall if it may affect photo uploads, but it's worth a shot.