Unable to automatically add events shared with external groups

Problem

When you invite an external group as a guest of a Calendar event the event is not being added automatically in the calendar of the members of the group.

Environment

Google Groups settings
Admin Console
Google Calendar

Solution

Only users within the same domain of the group can view the members of the group.
The members of the group have to manually add the event to their calendar by responding to the RSVP (Yes, Maybe, No).

Cause

Only if the user can view the members of the group the event will be automatically added to Calendar.
External users can't view the members of the groups.