Editor Broken for Contributors

[ Moderator note: Topic title corrected. ]

As an Admin I can use the Editor just fine.

But when logging in as a Contributor, I cannot see past uploaded images (https://i41.tinypic.com/2i0yhx2.png), or insert an image into a post. I also cannot insert pre-filled templates, and so on.

I’ve de-activated plug-ins + changed the theme but that hasn’t fixed anything.