Projector working in Editor, but disappearing after Build & Run

This is a bit of strange one I think and not sure why it's not working.. I created a projector using scripts for a terrain grid sqr so it would follow the mouse and highlight the grid tile that a ray hits. Works great when I run the game using play button inside Unity editor, but as soon as I build and run the project as exe, the projector isn't there anymore and not sure why. I'll copy in some of the code I've got for it.

 private float brushSize = 4.0f;
 private Texture2D brushes;
 private int brushSizePaint = 3;
 
 void Start(){
 brushes = Resources.LoadAssetAtPath("Assets/PATileTerrain/Brushes/patileterrain_brush1.png", typeof(Texture2D)) as Texture2D;
 
 InitPreview();
 }
 
     public void InitPreview(){ 
 
         
         GameObject previewObject = new GameObject("PATileTerrainPreview");
         previewObject.hideFlags = HideFlags.HideInHierarchy;
         previewProjector = previewObject.AddComponent<Projector>();
         previewProjector.nearClipPlane = terrain.settings.minHeight - 1.0f;
         previewProjector.farClipPlane = terrain.settings.maxHeight + 1.0f;
         previewProjector.orthographic = true;
         previewProjector.orthographicSize = brushSize;
         previewProjector.transform.Rotate(-90.0f, 0.0f, 0.0f);
          
         Shader previewShader = Shader.Find("Hidden/PATileTerrainPreview");
           Material previewMaterial = new Material(previewShader);
         previewMaterial.SetColor("_Color", new Color(0.32f, 0.36f, 0.6f, 0.07f));
         previewMaterial.SetTexture("_Brush", brushes);
         previewProjector.material = previewMaterial;
         
         previewProjector.enabled = true;
         
         /*[1.04]*/ previewProjector.transform.parent = terrain.transform; 
     }
 
     public void UpdatePreview()
     {
         if (previewProjector)
         { 
             
             previewProjector.nearClipPlane = terrain.settings.minHeight - 1.0f;
                 previewProjector.farClipPlane = terrain.settings.maxHeight + 1.0f;
                 previewProjector.material.SetColor("_Color", new Color(0.32f, 0.36f, 0.6f, 0.97f));
                 previewProjector.material.SetTexture("_Brush", brushes);
                 
             
             if (show3x3){
                 previewProjector.orthographicSize = (terrain.settings.tileSize * 0.6f)* brushSizePaint;
             
             }else previewProjector.orthographicSize = terrain.settings.tileSize * 0.6f;
             }
 }
 
     void Update () 
     {
         // ** THIS SECTION GETS POINTS using raycasts & x,y for tile seleciton ** 
         RaycastHit hit;
         Ray ray = Camera.mainCamera.ScreenPointToRay(Input.mousePosition);
         Physics.Raycast(ray, out hit, Mathf.Infinity);
         int x, y;
         Vector3 pos;
         pos = terrain.transform.InverseTransformPoint(hit.point);
         x = (int)Mathf.Abs(pos.x / terrain.tileSize);
         y = (int)Mathf.Abs(pos.z / terrain.tileSize);
         // ** THIS SECTION GETS POINTS ** 
             
         //uses the previewProjector created object to show highlighted grid sqr.
         PATileTerrain.PATile selectedTile = terrain.GetTile(x,y); //called every update so tile position is used in IF statement to update mousemovement
         //as long as tile and projector are assigned values, show highlighted projector on map.        
         if (selectedTile != null && previewProjector != null){
             previewProjector.transform.position = terrain.transform.TransformPoint(selectedTile.position);
             previewProjector.transform.rotation = terrain.transform.localRotation;
             previewProjector.transform.Rotate(90.0f, 0.0f, 0.0f);
         }//end if on projector.
 }