How to restore "groups" for RHEL7 yum?

It appears that the disc packages and repos you create by copying the files from the disc no longer provide support for package 'groups'. I found only one discussion here, but there are a plethora of Internet posts about groupinstall and other package -group commands no longer working.

I'm not sure if this problem also exists for systems that use online/Internet repos from redhat.com, but there seems to be a general lack of group package support lately.

Is there an official statement from Red Hat on why this is so, what changed, and what we can do to restore functionality locally, if necessary?

[root@data1 ~]# yum groupinstall "GNOME Desktop" --setopt=group_package_types=mandatory,default,optional
Loaded plugins: langpacks
Warning: group GNOME Desktop does not exist.
Maybe run: yum groups mark install (see man yum)
No packages in any requested group available to install or update