UI Button not correctly working

Hello, i'm new in Unity and trying to make an UI for my game. The UI is simple ,when i'm pressing "Escape" it displays the canvas and if i'm pressing "Escape" or click on the button "Return" it goes back to the game.

I freeze the game with Time.scaleTime = 0; while the canvas is on, but when i go back with the button it does not work and stay freeze, but with the key it works. If i set a Debug.Log it's only triggered with the key.

Can somebody explain why the button is not working ? Note : The canvas is disabled when the button is pressed

Here's the code i use :

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class GameManager : MonoBehaviour
 {
     private bool _playing;
     public GameObject canvas;
 
     // Start is called before the first frame update
     void Start()
     {
         _playing = true;
     }
 
     // Update is called once per frame
     void Update()
     {
         if (Input.GetKeyDown(KeyCode.Escape)) {
             UpdateUI();
         }
     }
 
     public void UpdateUI()
     {
         _playing = !_playing;
         canvas.SetActive(!_playing);
         Time.timeScale = (_playing ? 1 : 0);
     }
 }

 //using System.Collections;
 //using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 using UnityEngine.SceneManagement;
 
 public class BtnScriptGame : MonoBehaviour
 {
     private Button _btn;
     private GameManager _gm;
     public int btnType;
 
     // Start is called before the first frame update
     void Start()
     {
         _btn = GetComponent<Button>();
         _gm = GameObject.Find("GameManager").GetComponent<GameManager>();
         switch (btnType)
         {
             case 0:
                 _btn.onClick.AddListener(ResumeGame);
                 break;
             case 1:
                 _btn.onClick.AddListener(ResetRoom);
                 break;
             default:
                 _btn.onClick.AddListener(QuitRoom);
                 break;
         }
     }
 
     private void ResumeGame()
     {
         _gm.UpdateUI();
     }
 
     private void ResetRoom()
     {
         SceneManager.LoadScene(SceneManager.GetActiveScene().name);
     }
 
     private void QuitRoom()
     {
         SceneManager.LoadScene("Scenes/title_screen");
     }
 }