Domain Mapping Redirect Loop when using the mapped domain

Hi Folks

We have a wordpress multisite (Sub Domain) With a Wildcard SSL in place.

When we use the mapped domain we get a redirect loop. when we use the original domain then we can reach the site without an issue and the SSL works fine.

We have no caching on the server its running whm, cPanel on Centos.

No matter what settings we try for example, original domain, mapped domain or domain entered by user, as soon as you enter the mapped domain its an instant redirect loop.

Any Ideas?