Input.GetMouseButtonDown not working in Play mode

Hi! I don't know why Input.GetMouseButtonDown(0) not working in Play mode, but if i build&run - it's works good.

Why? This is my code:

 using UnityEngine;
 using System.Collections;
 
 public class Spawner : MonoBehaviour {
     public static Spawner Instance { get; private set; }
     public GameObject area;
     public GameObject enemy;
     public GameObject player;
     public float scaleX, scaleY, startPoint, minY, maxY;
     public bool gameRunning;
     public float enemyDefaultSize = 0.2F;
 
     void Awake() {
         gameRunning = true;
         Instance = this;
     }
 
     void Start () {
         scaleX = area.transform.localScale.x;
         scaleY = area.transform.localScale.y;
         startPoint = scaleX / 2;
         minY = (-area.transform.localScale.y / 2)+0.2F;
         maxY = (area.transform.localScale.y / 2)-0.2F;
         CallEnemy ();
         spawnPlayer ();
     }
 
     void spawnPlayer(Vector3 pos = default(Vector3)) {
         float spawnPlayerPoint = (scaleX / 2)/2;
         float startY = Random.Range (minY, maxY);
         player.GetComponent<Player> ().damage = 20;
         player.GetComponent<Player> ().fireDelaySet = 1.0F;
         if(pos == Vector3.zero) Instantiate (player, new Vector3(-spawnPlayerPoint, startY, -1), Quaternion.identity);
         else Instantiate (player, new Vector3(pos.x, pos.y, -1), Quaternion.identity);
     }
 
     public void CallEnemy() {
         float startY = Random.Range (minY, maxY);
         Instantiate (enemy, new Vector3(startPoint, startY, -1), Quaternion.identity);
         enemy.name = "Bot";
     }
     
 
     void Update () {
         if (gameRunning) {
             Debug.Log ("Test message");
             if (Input.GetMouseButtonDown (0)) {
                 Debug.Log ("Clicked!");
                 spawnPlayer (); //Work in Build&Play, but not in Editor(Play mode)
             }
         }
     }
 }