You are not the only one. It does not work. It seems to have worked before I started and there is one person who has me in their friend list and can visit my farm, but on my side I keep seeing 'Send Reminder'. I can do that 100 times, and she gets that message, but clicking it does not change anything in the game.
And most people do not show up at all in my game. I noticed that once I succeed in adding them to my Messenger contacts, they do show up in the 'friends ladder' of the game, but still with the text 'Send Reminder'. Other contacts I don't see at all.
And adding contacts to Messenger does not work either. When I try to, I get: Please wait while the contact is added to your Messenger list.
And then: Your request to add a contact has taken longer than expected to complete. The operation may have succeeded. Please check your messenger list later.
And then nothing happens... So frustrating.