The unlock says : "Finish the game with more than two friends", which means you need atleast three people with relationship above 49. If you had only Suong and Billy as a friend and didn get the unlock, then everything works correctly. If you had more people with relationship of 50 and more, then something is broken. Please check again how many friends you had and if you had 3+, then I will do some digging and see what's wrong.