Messages are not reaching the client (spotted on dedicated server)

[Mikeyfry]

Messages from players are shown in the log. But they do not come to the chat server GUI and in the game itself. Sometimes only messages from 1 player are visible to everyone. I haven't found a pattern as to why this happens.
 

function myCall.onPlayerTrySendChat(id, message, all)
   log.write("MESSAGE", log.INFO, "("..id..")"..clients[id].name.." "..message) --we make sure in the log that the player sent a message. But the message is not visible in the game
end