This bug is a little weird. Basically images were working fine in 0.8.4. However, after my upgrade to 0.8.6 the use_ssl flag was ticked in setting although ssl isn’t set up. It caused some weird issues with images.
When viewing a post, the image url is prefixed with https: https://example.com/uploads/4/jsd7fsfsy8379.gif etc. But if you open the post to edit, the url is a plain http://example.com url. Why the discrepancy?
The second issue is that I unticked the use_ssl option and posted another image post. This time it was visible, but none of the others were. I went back to the main page and then entered the thread again and the url had become an https://eexample.com url but the use_ssl option was still disabled.
The third thing that may be relevant is in another old thread from before the upgrade there are two images which are visible whether the flag is on or off. However, when i upgraded I blew away the old discourse folder and had to manually copy these two images form the /tmp/discourse backup I had made.
All ownership and permissions on all images are the same.