Firefox? I've seen FF occasionally cache broken headers very aggressively. Can sometimes fix by opening the history view (ctrl+H for many OS's), finding the URL in question, right-click and "forget about this site."
(Image is working for me on FF38 w/disconnect and ublock)
(no subject)
Date: 2015-06-16 08:17 pm (UTC)(no subject)
Date: 2015-06-18 07:08 pm (UTC)(no subject)
Date: 2015-06-18 07:09 pm (UTC)(no subject)
Date: 2015-06-19 01:11 am (UTC)https://36.media.tumblr.com/05260712e44fb57fdab1a1e092897509/tumblr_nk05wcew7X1ra4z4yo1_1280.jpg
(no subject)
Date: 2015-06-22 01:46 pm (UTC)(no subject)
Date: 2015-06-23 06:44 pm (UTC)(Image is working for me on FF38 w/disconnect and ublock)