Guys,
The past few days I've noticed images from imgur used with the image tag, not showing up in the posts. As far as I kow, the problem is caused by imgur itself as other image hosting sites work just fine.
I don't know when the issues get resolved, but I have these tips for now:
-Do not wrap images from imgur in [img] tags. This will leave a link instead and makes the image atleast viewable on the site of imgur.
-A good alternative I have been using for several years now, is cubeupload.com . No registration required and easy to use site interface, and you can use the [img] tags for images hosted there.