One last chance with multisite

There is a limit to the number of times you can go around the same circle and I have just about reached that. I have checked out the other postings on this forum and it appears to be a problem for a number of other people as well.

I am trying to achieve 2 WordPress driven web sites each with their own TLD https://www.zuzzinternet.uk and https://www.healyenigmaclub.com.

zuzzinternet is the main site and I have set it up as a multisite, healyenigmaclub is site 2 and is zuzzinternet.uk/healyenigmaclub

The DNS for zuzzinternet.uk has a www CNAME set to zuzzinternet.uk

The .htaccess in the ../zuzzinternet.com/web folder is

## Default .htaccess file

<IfModule mod_rewrite.c>
  RewriteEngine On

  RewriteBase /
  RewriteRule ^index\.php$ - [L]

  # add a trailing slash to /wp-admin
  RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

  RewriteCond %{REQUEST_FILENAME} -f [OR]
  RewriteCond %{REQUEST_FILENAME} -d
  RewriteRule ^ - [L]
  RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
  RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
  RewriteRule . index.php [L]

</IfModule>

sunrise.php has been copied to the ../zuzzinternet.com/web/wp-content folder and wp-config.php has

define( 'WP_ALLOW_MULTISITE', true );
define('MULTISITE', true);

On the Network Admin Dashboard –> Sites –> All sites, I have two entries, one for zuzzinternet.uk, the second for zuzzinternet.uk/healenigmaclub

For zuzzinternet.uk/healenigmaclub –> info, the Site URL is set to https://www.zuzzinternet.uk/healyenigmaclub/

For zuzzinternet.uk/healenigmaclub –> settings, the siteurl and Home are both zuzzinternet.uk/healenigmaclub

On the Network Admin Dashboard –> Settings –> Domain mapping I have the correct IP address and the domain option 4 is ticked

On the Network Admin Dashboard –> Settings –> Domains I have one entry for Site Id 2, healyenigmaclub.com which is not the primary site (Setting this to primary causes the browser to show a redirect problem)

With this configuration, entering https://www.healyenigmaclub.com into the browser displays the correct page but the address bar show https://www.zuzzinternet.uk/healyenigmaclub/

How can I get the address bar to show https://www.healyenigmaclub.com ?