Minor fix - Users would be prevented from joining if the relay request arrived before the host knew that they had joined the lobby.

Assets/Scripts/Relay/RelayUtpClient.cs

         {
             // Don't react to our own messages. Also, don't need to hold onto messages if the ID is absent; clients should be initialized and in the lobby before they send events.
             // (Note that this enforces lobby membership before processing any events besides an approval request, so a client is unable to fully use Relay unless they're in the lobby.)
-            return id != m_localUser.ID && m_localLobby.LobbyUsers.ContainsKey(id) && (m_localUser.IsApproved || type == MsgType.PlayerApprovalState);
+            return id != m_localUser.ID && (m_localUser.IsApproved && m_localLobby.LobbyUsers.ContainsKey(id) || type == MsgType.PlayerApprovalState);
         }
         protected virtual void ProcessNetworkEventDataAdditional(NetworkConnection conn, MsgType msgType, string id) { }
         protected virtual void ProcessDisconnectEvent(NetworkConnection conn, DataStreamReader strm)

Assets/Scripts/Relay/RelayUtpHost.cs

         protected override bool CanProcessDataEventFor(NetworkConnection conn, MsgType type, string id)
         {
             // Don't send through data from one client to everyone else if they haven't been approved yet. (They should also not be sending data if not approved, so this is a backup.)
-            return base.CanProcessDataEventFor(conn, type, id) && (m_connections.Contains(conn) || type == MsgType.NewPlayer);
+            return id != m_localUser.ID && (m_localLobby.LobbyUsers.ContainsKey(id) && m_connections.Contains(conn) || type == MsgType.NewPlayer);
         }
 
         protected override void ProcessNetworkEventDataAdditional(NetworkConnection conn, MsgType msgType, string id)