UNET: Lobby players not spawning on joining client

I amextending the NetworkLobbyManager to create a game lobby:

 public class NLMExtender : NetworkLobbyManager
 {
   public override void OnLobbyStartHost()
   {
     GameObject.FindWithTag("MultiplayerRoom").GetComponent<MultiplayerRoom>().isHost = true;
   }
 }

I create a match like this which creates lobby players on the scene:

   /// <summary>
   /// Create a match
   /// </summary>
   public void CreateMatch()
     {
     networkMatch = gameObject.AddComponent<NetworkMatch>();
     
     CreateMatchRequest create = new CreateMatchRequest();
     create.name = "MS_" + Guid.NewGuid().ToString("N");
     create.size = 2;
     create.advertise = true;
     create.password = "";
 
     networkMatch.CreateMatch(create, OnMatchCreate);
     }
 
   /// <summary>
   /// When match is being created
   /// </summary>
   /// <param name="matchResponse"></param>
   public void OnMatchCreate(CreateMatchResponse matchResponse)
   {
     if (matchResponse.success)
     {
       matchInfo = new MatchInfo(matchResponse);
       Utility.SetAccessTokenForNetwork(matchResponse.networkId, new NetworkAccessToken(matchResponse.accessTokenString));
       networkLobbyManager.StartHost(matchInfo);
     }
     else {
       Debug.LogError("Create match failed");
     }
   }

And I join a room like this which does not create the lobby players on the client:

   /// <summary>
   /// Connects to the lobby
   /// </summary>
   public void ConnectToRoom(GameObject gameList, MatchDesc match)
   {
     networkMatch = gameObject.AddComponent<NetworkMatch>();
     gameList.SetActive(false);
     networkMatch.JoinMatch(match.networkId, "", OnMatchJoined); // connect to the room
   }
 
   /// <summary>
   /// When a lobby has been joined
   /// </summary>
   /// <param name="matchJoin">Result of joining a lobby</param>
   public void OnMatchJoined(JoinMatchResponse matchInfo)
   {
     if (matchInfo.success)
     {
       networkLobbyManager.StartClient(new MatchInfo(matchInfo));
     }
     else
     {
       Debug.LogError("Join match failed");
     }
   }

Is there anything here that can be the reason for this? Because when I added the NetworkLobbyManager to the game object trough the editor it worked, but not when I extend this class to my own script (for the ability to override). Am I missing something that automatically happens when doing it trough the editor?

This is how it looks in the editor today:

The error message which most probably is related to my problem:

RegisterHandler id:45 handler:OnClientAddPlayerFailedMessage UnityEngine.Networking.NetworkManager:StartClient(MatchInfo) MultiplayerRoom:OnMatchJoined(JoinMatchResponse) (at Assets/Scripts/GUI/Menus/Multiplayer/MultiplayerRoom.cs:81) UnityEngine.Networking.Match.c__Iterator0`1:MoveNext()