I have try, I have only this problem with Firefox (not chrome), same after cookie/cache clear, all chmod file is ok, if I call the file path inside the url, it's ok, but it's not displayed on the site (I have try on my site and here).
In addition, that't not your site as far as I'm aware so it's not a bug nor a support issue.
It appears to be a browser issue local to you.
As such I have moved it to off topic.