(Client Issues) My friend is unable to see when he is in a queue and cant accept ready check

When my friend joins me or anyone in a party for us to play together he is unable to see when the leader queues us into a game and when the ready check pops up he cant see it so he is unable to accept it and play with us. He has tried almost everything from re-installing the client to restarting the client, checking if there are files that are stopping the client from working properly. This problem has been going on for a few weeks now and it happens about 98% of the time. If anyone has any ideas on how to fix this please comment, it would be much appreciated.