Can't add friends to Find My Friends

In my Find Friends app on ios8 I can't seem to add any new friends. The add button is greyed out, and people who are following me have the "remove" or "ask to follow" options also greyed out. I've tried removing the app, even including all data, but the situation is the same once I re-install. Followers can see my location, and those who I've previously added I can also see their location.

I have no idea what I'm doing wrong.

Aby suggestions?