Cannot set Selection.activeObject (no errors, no clues)

Hello, ive got a problem. Namely, i need to drag hundreds of prefabs into the scene, have them automatically assigned to an parent of my choice, then automatically select the parent, because i need to take a look quickly. The prefabs have assigned a script;

 using UnityEngine;
 using System.Collections;
 using UnityEditor;
 
     [ExecuteInEditMode]
     public class EditorAutoPlacement : MonoBehaviour {
     
         public bool selectParent = false;
         public string parentName;
         [HideInInspector]
         public bool alreadyPlaced = false;
     
         void Awake()
         {
             if (Application.isEditor && !alreadyPlaced)
             {
                 transform.parent = GameObject.Find(parentName).transform;
                 alreadyPlaced = true;
                 if(selectParent)
                 {
                     SelectParent();
                 }
             }
         }
         void SelectParent(){
             Selection.activeObject = gameObject.transform.parent;
         }
     }

The selection does not change to the prefab's parent gameObject. I also tried Selection.activeGameObject = gameObject.transform.parent.gameObject and it did not work as intended. Cheers