Multisite network admin issues

Hi there, I was on with chat support earlier but didn't get very far, except for try disabling plugins. However, everything was working before I mapped a custom domain to the site, so I know it's not that.

My issue is when you go to My Sites > Network Admin > and then any of those links, like 'Sites', 'Dashboard' etc. I get re-directed to the login page and then it loops and doesn't log in. All sub-site dashboards and links work perfectly, just the network admin which does not.

The URL it is supposed to go to is like this:

However it re-directs to here:

I have this in my wp-config:
define('WP_DEBUG', false);
define('WP_ALLOW_MULTISITE', true);
define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', true);
define('DOMAIN_CURRENT_SITE', '':wink:;
define('PATH_CURRENT_SITE', '/':wink:;
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 1);
define( 'WP_MEMORY_LIMIT', '512M' );
*That last line added by WPMU Dev which fixed the sub-sites admins not working, but now those are great.

Extra information which will hopefully help; this is my Cloudflare and Cloudways domain setup:

When in my back-end, I am at this URL:

However when I hover over the network admin links, I see it pointing to this URL:

I noticed there's no 'www' there. Not sure if that has anything to do with it, but just want to point it out.

I have enabled the support access in my back-end. Any help is much appreciated. Thank you.