OnClientConnectedCallback isn't called

Using Unity 6, for some reason I get nothing from:

NetworkManager.Singleton.OnClientConnectedCallback

but OnClientDisconnectCallback works just fine. I know the client is connecting because the logs show it, and it shows when they disconnect, but OnClientConnectedCallback never runs.

    void Start()
    {
        NetworkManager.Singleton.StartServer();
        NetworkManager.Singleton.OnClientDisconnectCallback += OnClientDisconnected;  // works
        NetworkManager.Singleton.OnClientConnectedCallback += OnClientConnected;      // never works
    }

Best practice to register events before starting the session (also: DRY principle):

var netMan = NetworkManager.Singleton
netMan.OnClientDisconnectCallback += OnClientDisconnected;
netMan.OnClientConnectedCallback += OnClientConnected;
netMan.StartServer();

What does your OnClientConnected method look like?

You can also throw my NetworkEventLogger on the NetworkManager object to get guaranteed logs for all events.