Using Sharepoint 2013 on office 365, I am a site admin and have verified I have Full control on my team site.
However, when viewing groups, I can view/edit permissions on site admin group but I can't even view members of other groups. Seems strange that I can change permissions on the site admin group, but not the less powerful contributor or view only groups.
When viewing the other groups i get "You do not have permission to view the membership of the group." Yet i have full control on the entire team site.