With AJAX trailing slash could cause problems sometimes, but don't think it's that this time.
You could put die('xxx'); as first thing in your controller method.
If xxx appears when you go to URL, it means routing works, and issue must be with rest of the controller/model code. If xxx does not appear it's either routing or __construct method where you need to dig further.
I also see you have auth as default controller, which makes me think you have some sort of authentication going on?
