I can't see my friend

Hi.

I have a problem with the game. I can't see a friend in "chat with friend" but he see me. If he send me a message, I see the notification bit when I open the tchat, there isn't the message or my friend. So I can't invit my friend to play with me.
I can see his profile on google play game.
Does somebody can help me please.

 

This issue is well-known and you need to either play a battle or close and reopen the game and it should be solved

 

Thanks for your fast answer.
But we play to the game since 3 days. We have close and open the game a lot of times and I can't see my friend. I restart my phone too.
If I launch a "personalised battle", I see that I have 1 friend but when I want to invit, there is nobody.

 

I solve my problem.
He has invited me to a "personalised battle". I accept and on the menu I click on his profil and click on "add friend". Now I can he see on chat.