Unity only read the first connected Controller's input

Hello,

I am having big trouble with inputs, although I thought having implement all correctly...

Here is my actual problem, I have a simple script that do that just in order to see if the controller works

 public class InputManager : MonoBehaviour
 {
     public const float MAX_CONTROLLER = 2;
     public List<int> assignedController = new List<int>();
     void Update()
     {
         CheckNewController();
     }
 
     void CheckNewController()
     {
         Debug.Log("Joy1Start " +Input.GetButton("Joy1Start"));
         Debug.Log("Joy2Start "+Input.GetButton("Joy2Start"));
         for (var i = 1; i <= MAX_CONTROLLER; i++)
         {
             if (assignedController.Contains(i))
                 continue;
 
             if (Input.GetButton("Joy" + i + "Start"))
             {
                 Debug.Log("Add new player on controller" +i);
                 assignedController.Add(i);
             }
         }
     }

I have my Unity Input setup like this

And a white a black XBOX One controller.

Now, if I put the black controller first then the white, my Debug.Log("Joy2Start ") fire and the other is always false. no matter which button I press If I do the opposite, and plug the white first, then I have Debug.Log("Joy1Start ")and same Joy2 stay stay false...

I guess I am doing something wrong, but I can't see :x

Can you enlighten me ?

Thanks