Try a “display page source” in your browser.
Restating that it’s broke doesn’t help. You’re not giving us anything to work with. Without some kind of debugging, we aren’t going to able to help you solve the problem. There are thousands of users of this system that don’t see this problem, so it’s something specific to your installation. While it could be a systemic FreePBX problem, that likelihood is low - it’s probably something in your specific installation.
The JavaScript debugger should help you get a feel for what’s failing. There are also logs in the system that should be able to help you. Log into the console of the server as ‘root’ and look for the /var/log/httpd/error_log (or some derivative of that) and see what the server is saying about the webserver’s idea of the page. You might also need to check the /var/log/asterisk/full log to see if there’s a database or permissions issue that needs some attention.
There are literally a hundred things this could be, so we’re going to need to start helping us help you.