In case it's still not working for you, maybe it will help to know that Imgur preemptively blocked some IPs across the board (you didn't do anything wrong, but other people in your general area did), and if you contact support and let them know what your IP is, they will unblock you. I had this situation nearly a month ago, I didn't know it was still happening, but maybe that's the problem you're having. It got resolved really quickly after I wrote them. :)