[SOLVED] Procedural Poly Terrain not generating everything

This is my first time making a randomly generated terrain system with a mesh instead of the actual terrain thats already in Unity itself. I keeo having this problem where it only does 1 row of terrain then stops, instead of moving onto the next row.

Any help?

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class TerrainGeneration : MonoBehaviour {
 
     private Mesh mesh;
 
     public bool DrawGizmosEnabled;
     public int MapSizeX, MapSizeZ;
     public int MapSizeMultiplier;
     public float GizmoSize;
 
     public List<Vector3> vertices;
     public List<int> triangles;
     public List<Vector2> uvs;
 
     void Start () {
         List<Vector3> vertices = new List<Vector3>();
         GenerateTer ();
     }
 
     private void OnDrawGizmos () {
         if (DrawGizmosEnabled == true) {
             Gizmos.color = Color.green;
             for (int i = 0; i < vertices.Count; i++) {
                 Gizmos.DrawSphere (vertices[i], GizmoSize);
             }
         }
     }
 
     void GenerateTer () {
         
         for (int SizeX = 0; SizeX < MapSizeX; SizeX++) {
             for (int SizeZ = 0; SizeZ < MapSizeZ; SizeZ++) {
                 float MapHeight = Random.Range (0, 2.01f);
                 if (SizeX == 0 || SizeZ == 0 || SizeX == MapSizeX - 1 || SizeZ == MapSizeZ - 1) {
                     Vector3 position = new Vector3 (SizeX * MapSizeMultiplier, 0, SizeZ * MapSizeMultiplier);
                     vertices.Add (position);
                 } else {
                     Vector3 position = new Vector3 (SizeX * MapSizeMultiplier, MapHeight, SizeZ * MapSizeMultiplier);
                     vertices.Add (position);
                 }
             }
         }
 
         Vector3[] Vert = new Vector3[vertices.Count];
 
         for (int i = 0; i < vertices.Count; i++) {
             Vert[i] = new Vector3(vertices[i].x, vertices[i].y, vertices[i].z);
         }
 
         for (int i = 0; i < MapSizeX - 1; i++) {
             for (int v = 0; v < (MapSizeZ + MapSizeX); v++) {
                 triangles.Add (i);
                 triangles.Add (i + 1);
                 triangles.Add (MapSizeX + i);
                 triangles.Add (MapSizeX + i);
                 triangles.Add (i + 1);
                 triangles.Add (MapSizeX + i + 1);
             }
         }
 
         Debug.Log ("Vert Count: " + Vert.Length);
 
         GetComponent<MeshFilter>().mesh = mesh = new Mesh();
         mesh.name = "Procedural Terrain Mesh";
         mesh.vertices = Vert;
         mesh.triangles = triangles.ToArray();
         mesh.uv = uvs.ToArray();
 
         mesh.RecalculateBounds ();
         mesh.RecalculateNormals ();
     }
 }