When you see the above diagnostic message, finding the group in the right hand column is a perhaps time-consuming way.
The ‘page not found’ is a subgroup in a major group you can find by clicking on the “GROUPS” header on a MAIN page. You will see several ways to sort the major groups. The “recent activity” sort may give you the quickest way.
For instance, you will find the “Don’t Spank” subgroup in the “Parenting Little Heathens” major group.