Super admin not able to access /wp-admin/network/site-users.php

Hello there. I'm stumped! I'm not sure if the is a bug or I'm really not able to access this page? Can someone help me out.

When I set up the network I used a different username other than admin and I'm wondering if that's the problem. Is there a file I would need to edit/or swap out 'admin' with my username?

Thanks guys!