Imgur galleries used to show up with a nice onebox preview of the gallery, but this broke recently and just a link is shown. e.g.
I viewed this topic on Meta on May 26th and the preview was working, now it is not. The preview in the first post will show up if you try replying to that topic (or this topic), and pasting any imgur galley URL into the edit box, but you won’t see a preview for the URL you just pasted. The preview won’t be there if you refresh the page.
I saw the same behavior on a forum hosted at DiscourseHosting.com also on May 26th, when they were running 1.2. The behavior is still there this week with 1.3.