Procedural mesh creation issue

I'm very sorry. It's my fault. For explain better, I write a stupid example to post, with my big surprise, works like a charm. I'm pretty sure that the problem is elsewhere.

then, by way for apologies, i post the stupid script:

 using UnityEngine;
 using System.Collections;
 using System.Linq;
 
 public class ProceduralQuad : MonoBehaviour {
 
     [SerializeField] Material material;
 
     Mesh mesh;
     Color32 c = Color.red;
     Vector4 t = new Vector4(1, 0, 0, -1);
 
     void Start () { mesh = new Mesh(); }
     
     void Update () {
 
         mesh.Clear();
         mesh.vertices = new Vector3[] 
         {
             transform.right * -.5f + transform.up * -.5f,
             transform.right * -.5f + transform.up * .5f,
             transform.right *  .5f + transform.up * .5f,
             transform.right *  .5f + transform.up * -.5f
         };
         mesh.uv = new Vector2[] 
         {
             new Vector2 (0,0),
             new Vector2 (0,1),
             new Vector2 (1,1),
             new Vector2 (1,0)
         };
         mesh.uv2 = mesh.uv1;
         mesh.colors32 = Enumerable.Repeat(c, mesh.vertexCount).ToArray();
         mesh.triangles = new int[] { 0, 1, 2, 2, 3, 0 } ;
         mesh.normals = Enumerable.Repeat(-Vector3.forward, mesh.vertexCount).ToArray();
         mesh.tangents = Enumerable.Repeat(t, mesh.vertexCount).ToArray();
         mesh.RecalculateBounds();
 
         Graphics.DrawMesh(mesh, transform.position, transform.rotation, material, gameObject.layer);
     
     }
 }