This is probably going to sound sarcastic but I mean this sincerely, play with it lol
It seems bugged, I tried it just now and it worked but I have had trouble with it before, I couldn't locate the problem so I can't help more other then confirm that there is an issue of some kind. Oh course, usual tech support applies (example - try different browser, reset everything, clear cookies and internet history, etc). Also I would try to delete the image completely and reupload after doing the above.