Adding class causes all images to be inaccessible.

Adding a class to an image field causes all images to disappear and need to be reloaded, presets dont' generate, server permissions are fine.

I have had this happen on two sites.
New images are fine. uploading the same image on the field works, and you don't even have to save the node.

I think the module deletes drupal's knowledge of most images some how.