The problem is that the fos_comment_script.src = '/web/js/35a8e64_comments_1.js' doesn't exist, i cant access it, so no threads are added and nothing is displayed. I'm not receiving any errors, nothing, everything looks fine but nothing is happening. I am using async.twig.html and the javascript that is generated on my page looks like this :

// thread idvar fos_comment_thread_id = '309';// api base url to use for initial requestsvar fos_comment_thread_api_base_url = '/web/api/threads';// Snippet for asynchronously loading the comments(function() {var fos_comment_script = document.createElement('script');fos_comment_script.async = true;fos_comment_script.src = '/web/js/35a8e64_comments_1.js';fos_comment_script.type = 'text/javascript';(document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(fos_comment_script);})();

Answer