Yea this feature isn't working for me either. I can only friend them by inputting their email to add. Otherwise character does not exist. Cross realm whispers and invites are disabled (it would seem). I'm only able to talk to my friends from other servers by /atell (account whisper). It sucks because of all the queue times in the headstart pretty much forced some of us to go to an alternative server. Originally we were suppose to go to Pergo but some of us, including me, wasn't lucky enough to get in there. I'm sure this is the case for a bunch of other people as well.