12-06-2016 11:06 AM
I cannot invite a external Guests to a external Yammer group. It only works through the admin panel.
12-09-2016 07:18 AM
Just keep in mind that the guests you're trying to add cannot be "consumer" addresses (ie. outlook.com, gmail.com, yahoo.com, etc). If you're still having trouble, might want to raise a support ticket.