Why Does Adding to My SyncListStruct Break SyncVar?

So I tried making a SyncListStruct that didn't work. So then I tried just doing SyncVar on the same Game Object and that didn't work. After checking each portion of code I found out why my SyncVar wasn't working and it turns out that it was because of the line that adds to my SyncStructList. Question is why?

Inside my RandomSpawnLocation method I have the line vPosList.Add(tempVpos); which seems to prevent SyncVar from working.

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine.Networking;
 
 public class PickUpSpawner : NetworkBehaviour {
 
     public int spawnAmount;
     public GameObject PickUpPrefab;
     public Camera MainCam;
     float posX, posY, posZ;
     float randSide;
     Vector3 randomPosition;
     private GameObject ground;
     public GameObject currentGO;
     private Plane[] planes;
     NetworkClient _client;
     public List<GameObject> SpawnedList = new List<GameObject>();
     [SyncVar (hook="TestChanged")]
     private int test = 0;
     [SyncVar]
     private string syncName;
 
     public struct vPos
     {
         public Vector3 vector;
         public vPos(Vector3 v)
         {
             this.vector = v;
         }
     };
 
 
 
      private vPos tempVpos;
      public class vPosClass : SyncListStruct<vPos> { }
      vPosClass vPosList = new vPosClass();
 
     //SyncListStruct<vPos> vPosList = new SyncListStruct<vPos>();
     public List<Vector3> SpawnPositions = new List<Vector3>();
 
     void TestChanged(int testChange) {
         test = testChange;
     }
 
     // Use this for initialization
     void Start () {
 
         planes = GeometryUtility.CalculateFrustumPlanes(MainCam);
         ground = GameObject.FindGameObjectWithTag("Ground");
         
         //This would be used to resgister a handlers (So when a certain type of msg is sent to call a spcific method
         //NetworkServer.RegisterHandler(MsgType.SyncEvent, OnServerPopulateSpawnPoints);
         if (isServer)
         {
             SpawnPickUpObject();
 
             for (int i = 0; i < vPosList.Count - 1; i++)
             {
 
                 SpawnPositions.Add(vPosList[i].vector);
             }
             
             Debug.Log("<color=red> Server Test </color> " + test);
         }
         else
         {
 
             for (int i = 0; i < vPosList.Count - 1; i++)
             {
                 SpawnPositions.Add(vPosList[i].vector);
             }
             
             
         }
 
         Debug.Log("SPAWN Count: " + vPosList.Count);
         
     }
 
     // Update is called once per frame
     void Update () {
 
         if (isServer)
         {
 
             test = 5;
         }
         else {
             Debug.Log("<color=red> Client Test </color> " + test);
         }
 
         if (isServer)
         {
 
             syncName = "Setting Name on Server";
         }
         else
         {
 
             Debug.Log("<color=red> Client Updated? </color>" + syncName);
         }
 
         if (Vector3.Distance(MainCam.velocity, Vector3.zero) > 5.0f)
         {
             for (int i = 0; i < SpawnPositions.Count - 1; i++)
             {
 
                 //if random position is ever in view, spawn object
                 //if (MainCam.WorldToViewportPoint(SpawnPositions[i]).x <= 1 && MainCam.WorldToViewportPoint(SpawnPositions[i]).x >= 0 && MainCam.WorldToViewportPoint(SpawnPositions[i]).y <= 1 && MainCam.WorldToViewportPoint(SpawnPositions[i]).y >= 0)
                 if (InfiniteCameraCanSeePoint(MainCam, SpawnPositions[i]))
                 {
                     //Debug.Log("Got 1");
                     currentGO = Instantiate(PickUpPrefab, SpawnPositions[i], Quaternion.identity) as GameObject;
                     currentGO.transform.localScale = new Vector3(0.3f, 0.3f, 0.3f);
                     SpawnedList.Add(currentGO);
                     //Remove pos added as to not add there again
                     SpawnPositions.RemoveAt(i);
                 }
             }
         }
         else {
 
             for (int i = 0; i < SpawnedList.Count - 1; i++)
             {
                 if (!InfiniteCameraCanSeePoint(MainCam, SpawnedList[i].transform.position)) {
                   
                     Destroy(SpawnedList[i]);
                     //Add back the spawn we just destroyed, might set a timer on this to add after a certain period of time has passed, in which case a queue could be used of position to spawn?
                     SpawnPositions.Add(SpawnedList[i].transform.position);
                     SpawnedList.RemoveAt(i);
                     
                 }
 
             }
 
         }
     }
 
     public bool InfiniteCameraCanSeePoint(Camera camera, Vector3 point)
     {
         Vector3 viewportPoint = camera.WorldToViewportPoint(point);
         return (viewportPoint.z > 0 && (new Rect(0, 0, 1, 1)).Contains(viewportPoint));
     }
 
     public void SpawnPickUpObject() { 
     
         for (int i = 0; i < spawnAmount; i++) {
 
             RandomSpawnLocation();
             //currentGO = Instantiate(PickUpPrefab, randomPosition, Quaternion.identity) as GameObject;
             //currentGO.transform.localScale = new Vector3(0.3f, 0.3f, 0.3f);
             //SpawnedList.Add(currentGO);
             //Debug.Log(randomPosition);
 
         }
     
     }
 
     public void RandomSpawnLocation() {
 
         //X might be pos or neg
         randSide = Random.Range(0, 10);
         if (randSide <= 5)
         {
             posX = Random.Range(1, ((ground.GetComponent<Renderer>().bounds.size.x / 2) - 1));
         }
         else
         {
             posX = Random.Range(((ground.GetComponent<Renderer>().bounds.size.x / 2)) * -1, -1);
         }
         //z might be pos or neg
         randSide = Random.Range(0, 10);
         if (randSide <= 5)
         {
             posZ = Random.Range(1, ((ground.GetComponent<Renderer>().bounds.size.z / 2) - 1));
         }
         else
         {
             posZ = Random.Range(((ground.GetComponent<Renderer>().bounds.size.z / 2)) * -1, -1);
         }
 
         posY = 0.5f;
         randomPosition = new Vector3(posX, posY, posZ);
         tempVpos = new vPos(randomPosition);
         //Breaks syncVar
         vPosList.Add(tempVpos);
 
         //SpawnPositions.Add(randomPosition);
       
         //transform.position = randomPosition;
     
     }
 
 }