You are just moving too fast.
try with:
public float float speed = 0.1f
FixedUpdate(){
transform.position += Vector3.right * Time.fixedDeltaTime * speed;
}
Thanks for your answer, I tried that but it didn't change anything saddly for the trigger at (23,0,0), with the trigger at (35,0,0) It can move as I said, but with this speed it s very very slow.
Maybe I should stop trying to understand what is wrong and try to make progress in my prototype with the (35,0,0) that works ..