Respawning Navmesh and Prefabs

So I have a Enemy prefab that uses navmesh and follows my player around. The problem with this is that when I spawn an enemy after 10 seconds it just crashes into a wall and stays there. Here is my code, and it's attached to a immobile object. I have tried to do this without using a prefab and it works, but then I can't find a way to respawn.

 private var startTime : float;
 public var enemy : Transform;
 private var spawnLocation : int;
 
 function Update () 
 {
     spawnLocation = Random.Range(0,3);
     if (startTime == 0)
     {
         startTime = Time.time;
     }
     
     else
     {
         if ((Time.time - startTime) >= 10)
         {
             startTime = 0;
             
             if (spawnLocation == 0)
             {
                 Instantiate (enemy, Vector3(724.1563,3.100793,438.2945), Quaternion.identity);
             }
             
             else if (spawnLocation == 1)
             {
                 Instantiate (enemy, Vector3(805.3612,3.100793,491.1311), Quaternion.identity);
             }
             
             else if (spawnLocation == 2)
             {
                 Instantiate (enemy, Vector3(712.8903,3.100793,518.0007), Quaternion.identity);
             }
         }
     }
 }