URL Entered By User Not Working on Front End

There is a setting in the plugin's global settings that allows the domain mapper to use the domain a person enters in the url. I have it selected. So if someone goes to site.siteroot.com they should see that in the url. If they go to site.com they will see site.com.

It's not working. The domain mapping tool is redirecting the site.siteroot.com to the mapped domain. This is an issue. Please assist.