How do I reset a trigger after moving an object out of it?

Hello! I have a small problem with a trigger and bool. The small square has a trigger collider on it. When I push one of the buttons on the UI, an object is instantiated. I have set it up so that if I drag on the object with a mouse, the object moves away from the trigger. My problem is that the “is empty” bool doesn’t reset after I move the object away from the trigger. If I put an “is empty = true” in the update, then, of course, it’s always true and I can spawn multiple objects at the same time.

https://imageshack.com/i/pmvak8Ndp

I’ve tried the OnTrigger Enter/Exit combo and OnTriggerStay as well. I’m sure OnTriggerStay is probably the answer(?), but I think I’m missing some kind of logic or placement to ensure that the bool resets properly. I’m wondering if it’s because I put the same script on all of the buttons or because it’s not Instanced? I would appreciate any tips about what direction I should be taking. Thanks in advance!

using UnityEngine; using UnityEngine.UI;

public class InstantiateObjects : MonoBehaviour {

 public GameObject goPrefab;

 //list
 public List<GameObject> createdObjects = new List<GameObject>();

 //drop area
 public GameObject dropZone;
 public bool dropZoneEmpty;

 //game object limits
 public int gameObjectLimit;
 public int listSize;

 // Start is called before the first frame update
 void Start()
 {
     dropZoneEmpty = true;
 }

 private void Update()
 {
     listSize = createdObjects.Count;

 }

 // Update is called once per frame
 public void CreateObject()
 {
     if (dropZoneEmpty == true && listSize < gameObjectLimit)
     { 
         Vector3 position = dropZone.transform.position;

         //instantiate object
         GameObject go = (GameObject)Instantiate(goPrefab, position, Quaternion.identity);
         createdObjects.Add(go);

         dropZoneEmpty = false;
     }
 }

}