Forum Attachmets not showing
 

Hi, I set up a new dev forum, and now I have the problem that no attachment image is showing anymore, respectively getting loaded. When you click on a thumbnail (which are shown correctly) the lightbox opens and starts to load, but then nothing happens anymore. The indicated name and size of the image are correct, but the target image is simply not loading, new or old attached pictures, doesn't matter. Even when you let it run for minutes, it's just trying to load until you stop it. Not even an error message.

I double checked the following: all images/attachments are uploaded correctly. Storage type is set to images/attachments, the attachments folder is CHMOD 777. I also rebuilt all thumbnails.

I am kind of stuck now, do you have an idea what the reason could be? Running and dev forum are on the same server, so the server settings are the same and not an issue.

Thanks!