ScrollView stops working when you re-enter the scene

Hello. When you re-enter the scene, Scroll View stops working, does not scroll up and down. To fill it, I use the following code in the function:

Code (CSharp):

1. void FillList()
2.     {
3.         // create instants (level buttons)
4.         foreach(var level in LevelsList)
5.         {
6.             GameObject newbutton = Instantiate(levelButton) as GameObject;
7.             But_lvlUI button = newbutton.GetComponent<But_lvlUI>();
8.             button.LevelText.text = level.LevelText;
9.  
10.  
11.             if (PlayerPrefs.GetInt("Level" + button.LevelText.text) == 1)
12.             {
13.                 level.Unlocked = 1;
14.                 level.IsInteractable = true;
15.             }
16.  
17.             button.unlocked = level.Unlocked;
18.             button.GetComponent<Button>().interactable = level.IsInteractable;
19.             button.GetComponent<Button>().onClick.AddListener(() => Select_LVL(int.Parse(button.LevelText.text)));
20.  
21.             newbutton.transform.SetParent(Spacer);
22.             newbutton.transform.localScale = new Vector3(1, 1, 1);
23.             newbutton.transform.localPosition = new Vector3(transform.localPosition.x, transform.localPosition.y, 0);
24.         }
25.     }

Can you tell me what could be the problem?