Why can't my user see the private groups they are members in?
I think this has to do with publishing the content.

If I published a group that was marked as invite only, it would then show up in the list of groups as invite only, and content would only be viewable by members. Seems like an imperfect solution though, as to me, an invite only group should be hidden. But if you do use this solution, be sure to mark the content type to default to published.

There's problems with Drupal and unpublished content sometimes. In this case, the usual solution (Views won&#39;t display unpublished nodes when explicitly told to) didn't seem  to fix it.