Domain Mapping plugin not working

Experiencing an issue with Domain Mapping plugin not working. Site is hosted with SiteGround and external DNS records. Their tech support issued me these instructions on how to properly setup local DNS using external DNS within cPanel to handle external DNS.

They said:
In order to use external DNS zone and have the subdomains loading from the account here, you need to:

1) Remove the DNS zone entry you have created within the DNS editor:
* 14400 IN A 111.222.333.444

2) Create a WildCard subdomain for
* to point to home/public_html

which is the root folder of the domain
The actual WildCard subdomain you set will automatically set the A record as well, and it from there will detect the proper root folder, so it will be associated with the addon instead of the primary domain.
******End of Tech Response

Of course this didn't work.

Did external ping to verify Mapped Domain resolved to proper server ip. Health Status shows "Invalid" for mapped domain regardless that DNS is correct.

sunrise has been moved and not copied
htaccess updated
wp-config updated

I had tried hosting this site with other multisite installs on the same server and Domain Mapping wasn't working. To isolate the problem, I set up a server with only this multisite install. All by itself on the server Domain Mapping still does not work. Please advise.