assigning sprites to game object via script

Hi, im following a tutorial on youtube 'Unity Base Building Game'. The program so far has a few classes, an array of tiles of one of two types (at random for now) is created, each tile gets a game object, each game object gets a sprite renderer, then should get a sprite assigned. My issue is only one type of tile is getting a sprite assigned.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class GameWorldController : MonoBehaviour
 {
     public Sprite groundSprite;
     public Sprite waterSprite;
 
     Map map;
 
     // Start is called before the first frame update
     void Start()
     {
         map = new Map();
         
 
         for (int x = 0; x < map.Width; x++)
         {
             for (int y = 0; y < map.Height; y++)
             {
                 Tile tile_data = map.GetTileAt(x, y);
                 GameObject tile_go = new GameObject();
                 tile_go.name = "Tile_ " + x + "_" + y;
                 tile_go.transform.position = new Vector3(tile_data.X, tile_data.Y, 0);
 
                 tile_go.AddComponent<SpriteRenderer>();
                 tile_data.RegisterTileTypeChangedCallback( (tile) => { OnTileTypeChanged(tile, tile_go);  } );
 
 
             }
 
         }
         map.RandomizeTiles();
     }
 
     
     // Update is called once per frame
     void Update()
     {
         
     }
 
     void OnTileTypeChanged(Tile tile_data, GameObject tile_go)
     {
         if (tile_data.Type == Tile.TileType.Ground)
         {
             tile_go.GetComponent<SpriteRenderer>().sprite = groundSprite;
             Debug.Log("groundsprite added");
         }
         else if (tile_data.Type == Tile.TileType.Water)
         {
             tile_go.GetComponent<SpriteRenderer>().sprite = waterSprite;
             Debug.Log("watersprite added");
         }
         else
         {
             Debug.LogError("OnTileTypeChanged - Unrecocnised tile type.");
         }
     }
 }
 

Map class:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Map
 {
     Tile[,] tiles;
     int width;
     public int Width
     {
         get
         {
             return width;
         }
     }
     int height;
     public int Height { get
         {
             return height;
         }
     }
 
     public Map(int width = 100, int height = 100)
     {
         this.width = width;
         this.height = height; 
 
         tiles = new Tile[width, height];
 
         for (int x = 0; x < width; x++)
         {
             for (int y = 0; y < height; y++)
             {
                 tiles[x,y] = new Tile (this, x, y);
             }
         }
         Debug.Log("World created with " + (width * height) + " tiles.");
         
     }
 
     public void RandomizeTiles()
     {
         Debug.Log("RadomizeTiles");
         for (int x = 0; x < width; x++)
         {
             for (int y  = 0; y < height; y++)
             {
                 if (Random.Range(0, 2) == 0)
                 {
                     tiles[x, y].Type = Tile.TileType.Ground;
                     Debug.Log("Ground!");
                 }
                 else
                 {
                     tiles[x, y].Type = Tile.TileType.Water;
                     Debug.Log("Water!");
                 }
             }
 
         }
     }
 
     public Tile GetTileAt(int x, int y)
     {
         if (x > width || x < 0 || y > height || y <0)
         {
             Debug.LogError("Tile (" + x + "," + y + ") is out of range");
             return null;
         }
         return tiles[x, y];
      
     }
 
 }

Tile class:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using System;
 
 public class Tile
 {
     public enum TileType { Ground, Water };
 
     TileType type;
 
     Action<Tile> cbTileTypeChanged;
 
     public TileType Type
     {
         get
         {
             return type;
         }
         set
         {
             TileType oldType = type;
             type = value;
 
             if (cbTileTypeChanged != null && oldType != type)
             {
                 cbTileTypeChanged(this);
                 Debug.Log("TileTypeChanged");
             }
         }
     }
 
     LooseObject looseObject;
     InstalledObject installedObject;
 
     Map map;
     int x;
     public int X
     {
         get
         {
             return x;
         }
     }
     int y;
     public int Y
     {
         get
         {
             return y;
         }
     }
 
     
 
     public Tile (Map map, int x, int y)
     {
         this.map = map;
         this.x = x;
         this.y = y;
     }
 
     public void RegisterTileTypeChangedCallback(Action<Tile> callback)
     {
         cbTileTypeChanged += callback;
     }
     public void UnRegisterTileTypeChangedCallback(Action<Tile> callback)
     {
         cbTileTypeChanged -= callback;
     }
 }
 

As you can see ive put some debug logs in and I never see the "groundsprite added" log, i do howver see the "ground!" and "water!" logs, indicating the tile types are indeed changing.