The answer I believe is the one given to me by KCullen-esristaff<https://community.esri.com/people/KCullen-esristaff> in that thread (although we'd figured it out by the time I got the response). It is counter intuitive but you see the group only through your own content that you want to share until update access which is not what you'd think you were doing.
Paula Kay Lazrus, Ph.D.
Associate Professor
Institute for Core Studies
St. John's University
St. John's Hall B3a-1
8000 Utopia Parkway
Queens, NY 11439
718-990-2685