Issues with add friend

Hi, I'm trying to add friends but even if I copy/paste their names (Åkela), it says ''The player Åkela does not exist''. To be sure it's well written, I tried to find my friend's profile with same copy/paste and it works. Weird!

I already tried to join a game with him, which I can invite him by searching his username, but even in recently played with, if I press the ''add friend'' button, neither he or I receive any friend request.

Both of us has special characters in our usernames.

Any suggestions? Thanks