1. The domain mapping seems to be missing the directory as you can see when I visit ambassadordowns.com, I get the directory listing that is missing the multisite sunhome.properties directory ...
Index of /
Apache Server at ambassadordowns.com Port 80
2. I parked the domain ambassadordowns.com in cpanel
3. my config.php contains
define( 'WP_ALLOW_MULTISITE', true );
$base = '/';
/* define( 'DOMAIN_CURRENT_SITE', '127.0.0.1/~username/installedblog/' ); */
4. sunhome.properties is an addon domain that is is running the multisite using sub-directories
Manage Addon Domains
Addon Domain Username Website Folder or Redirect
sunhome.properties admin public_html/sunhome.properties
Spent over 6 hours on this issue and bought into wpmudev partly to get me over this hiccup and also the backup a whole multisite plugin. Surprised there is no security plugins, in the membership, as a side point.