When I create a new group category and create groups in that category, I get an error message if I try to view the group members. However, when I create a new group under an existing (old) category, I can view the members without any problems.
To make sure it wasn't a category settings issue, I saved an existing old category and changed the name.
The error message is COM_EASYSOCIAL_GROUP_DOES_NOT_HAVE_ACCESS
I get this message even if I use the super admin login.