OnTriggerExit not called for Tree painted on Terrain

more information could help, like what components are on the GameObjectswith the trigger? does it have a rigidbody? does the tree has a rigidbody and so on. also sharing more of the code could help too.

is the OnTriggerEnter called?

anyway i would make sure that the GameObjects are set right. in order to trigger OnTriggerExit you need at least one of the GameObjects to have a rigidbody. ( as you can see on this page)

 using System.Collections.Generic;
 using UnityEngine;
 
 public class $$anonymous$$4Obstaclerator : $$anonymous$$onoBehaviour
 {
     public bool UNRESOLVED { get; private set; }
     public int DegreeJump = 30;
     public Layer$$anonymous$$ask Blocking;
     private bool _blocked;
     private int _layer;
     private int[] _steps;
     private int _i;
 
     public void Awake()
     {
         _blocked = true;
         _steps = new int[360 / DegreeJump];
         var counter = 0;
 
         foreach (var num in nextAngle())
         {
             if (counter == _steps.Length)
                 break;
             _steps[counter++] = num;
         }
     }
 
     public void OnTriggerExit(Collider other)
     {
         if (other.gameObject.layer == _layer)
         {
             Debug.Log("OnTriggerExit: " + other.gameObject.name);
             _blocked = false;
         }
     }
 
     public void OnTriggerEnter(Collider c)
     {
         if (((1 << c.gameObject.layer) & Blocking) != 0)
         {
             Debug.Log("OnTriggerEnter: " + c.gameObject.name);
             _blocked = true;
         }
     }
     
     public void SetColliderLayer(int layer)
     {
         _layer = layer;
     }
 
     public Transform FoundTarget()
     {
         if (_blocked)
         {
             transform.parent.RotateAround(transform.parent.position, transform.up, getDegree());
             return null;
         }
         return transform;
     }
 
     private int getDegree()
     {
         if (_i < _steps.Length)
             return _steps[_i++];
         
         UNRESOLVED = true;
         return 0;
     }
 
     private IEnumerable<int> nextAngle()
     {
         var iRight = 1;
         var iLeft = -2;
         while (true)
         {
             yield return iRight * DegreeJump;
             yield return iLeft * DegreeJump;
             iRight += 2;
             iLeft -= 2;
         }
     }
 }

Here is the entire script of the gameObject that i want the OnTriggerExit/Enter to get called. This gameObject that is being rotated only has a box collider with the "Is Trigger" checked and this script attached. Okay i have a render mesh on it as well because i want to see what it is doing for now, hence the big green box in the videos. The Tree Prefab has a RigidBody component.
So it works as expected when i manually place a tree in the scene, but not when i use the same tree with the Terrain tool. The Terrain tool is doing something else that i am unaware of or treats collisions differently to the Prefab - i guess.

i notice that the collider returned from the collision was that of the terrain, not any individual tree. I cannot find it now, but someone recommended a mass placement tool, which seems to be my solution.
What i am trying to do is a simple navigation around a small obstacle that may or may not be there. I don't think the nav$$anonymous$$esh works for dynamic objects? There will be other tanks moving around, or not (knocked out). For larger objects i have a path with target points that will be used to negotiate it.
i am very new to Unity, so my approach will be more than likely wrong! Thanks for the help.

nav$$anonymous$$esh looks like it has a place when building a game, but it doesn't suit me on this occasion. Anyway, onwards i go!