Dev Dashboard within site

I've recently updated the email address I first registered with WPMU (as part of a major rebrand the domain associated with that email is being phased out).

As such, I've begun to update my user accounts on the sites I use WPMU plugins and I've run into a problem:

When logged in under the user account that has my new email (now the only email on record for my account here) I cannot see the WPMU Dev dashboard.

I'm using:
define('WPMUDEV_HIDE_BRANDING', true);
in my wp-config file – I don't want to remove this as I don't want other users to be able to see the dev dashboard.

Why would I not be able to see WPMU dev dashboard when logged in with my WPMU registered email?