OnServerStart not being called in standalone build. Works in editor.

Unity 5.5.2f1
I have implemented an override of OnServerStart in my GameMananager class:

public class GameManager : NetworkBehaviour
{
    static GameManager _manager = null;
    public static GameManager Instance { get { return _manager; } }

    ShipManager _shipManager;

    void Awake()
    {
        if (_manager == null) _manager = this;
        else if(_manager != this) Destroy(gameObject);

        DontDestroyOnLoad(gameObject);

        _shipManager = GetComponent<ShipManager>();
    }

    #region Overrides of NetworkBehaviour

    public override void OnStartServer()
    {
        base.OnStartServer();
        Debug.Log("OnStartServer Running...");
        _shipManager.LoadShips();
    }

    #endregion
}

When I run in the editor as “Host”, OnStartServer runs and my ships are created.
However, when I build and run in standalone mode, nothing happens. The log does not indicate that OnStartServer was ever called. What am I missing here?

Ever found a solution? I have almost the same problem.

I have a script that derives from NetworkManager and has

public override void OnStartServer()

{

base.OnStartServer();

Debug.Log(“OnStartServer running…”);

}

It is never called, not even in the editor (version 2018.3.5f1)