Problems with Colorbox

Oh, that is not very easy to debug. Could you post a list of all enabled modules here?

Hey hermanns, let us try to fix that issue so please post a list with all your enabled modules.

I too have this bug

I also have this problem. When the formatter in 'manage display' is set to colorbox, the class is not saved. If you change the format back to 'image', it works. So I think there is a conflict with the colorbox module.

Same issue. This also happens with lightbox.

I add the classes in the formatter and update. Classes are saved. However when I save the display the classes are removed.

See the images I posted here > https://www.drupal.org/node/2697145

The only modules you need to show this problem are the Image Class module (7.x-1.0) and the Colorbox module (7.x-2.12) and their dependencies.

Note that this is also using the Bootstrap theme with the Responsive image setting turned on to add 'img-responsive' to all IMG tags, Disabling that setting does not affect the removal of the class added via Image Class.

Eric

Fixed for colorbox module.

A better version of the patch.