How do set the initial position of a rigidbody with a network transform.

I have a button that spawns in a gameobject with a Network Rigidbody and a Network transform.

The game object prefab is at (0,0,0). But If I want to set an initial position to (-3,0,0), what I see on the client is an object spawning at (0,0,0) then quickly sliding into place at (-3,0,0).

Even if I look carefully on the server instance, I see a brief flash where the object is at (0,0,0).

What am I missing here?

Code (CSharp):

1.  
2.  
3. public class RobotControl : NetworkBehaviour
4. {
5.     new private Rigidbody rigidbody;
6.  
7.     public Vector3 defaultPosition = new Vector3(-3, 0, 0);
8.  
9.     public override void OnNetworkSpawn()
10.     {
11.         if (NetworkManager.Singleton.IsServer){
12.             rigidbody = GetComponent<Rigidbody>();
13.             rigidbody.position = defaultPosition;
14.         }
15.     }
16. }
17.  

I'm running netcode 1.2.0