I have enabled Organic Groups and Organic Groups UI.
I have created a content type "Group" and enabled it as a group content type. I have created a new piece of content using the Group type and set it to be a group. I am the group manager.
I set Basic Page to be group content.
When I create a Basic Page, it has a Groups Audience field, but the list of "Your Groups" is empty (containing only "-None-"). Since I am an administrator, I also get a searchable field for "other groups" but nothing turns up when I begin typing the name of the only group on my site.
I'm sure I have missed a basic setting somewhere, but I can't figure out what it is!