It seems the program does not refresh this correct for me either.
1. hit the home button on the ipad/ipod to get back to the main screen
2. hit the home button twice so that it shows you the list of running apps
3. press and hold on the tapped out app icon until it show the minus in the corner.
4. click the tapped out icon again and it will close the app.
5. open it again then you should have your friends.
I have to do this almost every time I get a new friend.
Add me, Briankosa