Super Admin: Unable to Login - No error message - New Multisite

I've created a new multisite. Wildcard domains have been set up in DNS and CPANEL. In the wp-config file I've set the subdomains to 'true'. The Site registers new users and creates new sites flawlessly. One plugin was installed with WPMU updates: "Ultimate Branding Plugin"

I changed the login image within the branding plugin, then logged out to see how it looked. However, I was unable to log back in. After submitting user and password, I didn't receive an error message. I tried to register a new password through 'I forgot my password' link and new password registration in email. Still no results. There was no error message and the page was unresponsive other than my username and password disappeared. After looking into this issue on Google, I found ways to trouble shoot. Turns out when I have SUBDOMAINS: 'true' within my wp-config.php file, I'm unable to log in as a super admin.

Is there a way to fix this so that I can access the super-admin without having to edit the wp-config.php file each time I login?