Space Shooter: Asteroids not being destroyed

I haven't seen a solution for this yet so I'm hoping you guys can help me out. I have been going through the Unity Space Shooter tutorial and making good progress. I ran into a problem though at Step 11, Explosions. I continue to Step 13, Spawning Waves, hoping that the problem would resolve itself but nothing happened.

The asteroid that is created for the game reacts fine when it is in the hierarchy tabs, spawning and interacting with all objects as it should(being destroyed when it comes into contact with my ship, bolts or the game boundary). I've moved the asteroid into the prefab, it also worked as expected.

The problem happens when I go to the game controller and drag the drop the asteroid in the hazard tab. Once dropped in, the game plays and the hazard spawn but they do not interact, even with the game boundary and they continue to spawn and never leave the game. I have restarted unity, restarted my computer and replaced the code with the code at the bottom of the page. I'm not sure what is wrong and could use your help guys. I'll post the code bellow, thank you.

Destroy By Contact

 using UnityEngine;
 using System.Collections;
 
 public class DestroyByContact : MonoBehaviour
 {
     public GameObject explosion;
     public GameObject playerExplosion;
     
     void OnTriggerEnter(Collider other) 
     {
         if (other.tag == "Boundary")
         {
             return;
         }
         Instantiate(explosion, transform.position, transform.rotation);
         if (other.tag == "Player")
         {
             Instantiate(playerExplosion, other.transform.position, other.transform.rotation);
         }
         Destroy(other.gameObject);
         Destroy(gameObject);
     }
 }
 

Destroy By Boundary

 using UnityEngine;
 using System.Collections;
 
 public class DestroyByBoundary : MonoBehaviour
 {
     void OnTriggerExit(Collider other)
     {
         Destroy(other.gameObject);
     }
 }

Player Controller

 using UnityEngine;
 using System.Collections;
 
 [System.Serializable]
 public class Boundary
 {
     public float xMin, xMax, zMin, zMax;
 }
 
 public class PlayerController : MonoBehaviour 
 {
     public float speed;
     public float tilt;
     public Boundary boundary;
 
     public GameObject shot;
     public Transform shotSpawn;
     public float fireRate;
 
     private float nextFire;
 
     void Update()
     {
         if (Input.GetButton("Fire1") && Time.time > nextFire) 
         {
             nextFire = Time.time + fireRate;
 //            GameObject clone = 
             Instantiate(shot, shotSpawn.position, shotSpawn.rotation); //as GameObject;
         }
     }
 
     void FixedUpdate ()
     {
         float moveHorizontal = Input.GetAxis ("Horizontal");
         float moveVertical = Input.GetAxis ("Vertical");
 
         Vector3 movement = new Vector3 (moveHorizontal, 0.0f, moveVertical);
         rigidbody.velocity = movement * speed;
 
         rigidbody.position  = new Vector3
         (
             Mathf.Clamp (rigidbody.position.x, boundary.xMin, boundary.xMax),
             0.0f,
             Mathf.Clamp (rigidbody.position.z, boundary.zMin, boundary.zMax)
         );
         rigidbody.rotation = Quaternion.Euler (0.0f, 0.0f, rigidbody.velocity.x * -tilt);
     }
 }

Game Controller

 using UnityEngine;
 using System.Collections;
 
 public class GameController : MonoBehaviour
 {
     public GameObject hazard;
     public Vector3 spawnValues;
     public int hazardCount;
     public float spawnWait;
     public float startWait;
     public float waveWait;
     
     void Start ()
     {
         StartCoroutine (SpawnWaves ());
     }
     
     IEnumerator SpawnWaves ()
     {
         yield return new WaitForSeconds (startWait);
         while (true)
         {
             for (int i = 0; i < hazardCount; i++)
             {
                 Vector3 spawnPosition = new Vector3 (Random.Range (-spawnValues.x, spawnValues.x), spawnValues.y, spawnValues.z);
                 Quaternion spawnRotation = Quaternion.identity;
                 Instantiate (hazard, spawnPosition, spawnRotation);
                 yield return new WaitForSeconds (spawnWait);
             }
             yield return new WaitForSeconds (waveWait);
         }
     }
 }