Can't generate 3D meshes via script

So, i created a really simple script (suck at programming) to generate a 3D mesh of an hexagon, and when i run it, it looks like the mesh gets flattened out, so instead of getting a 3D mesh, i get a 2D mesh of the hexagon. The fun part is that my script actually works, it generate a 3D mesh (At leats, that's what my mesh filter say; And my vertices are in the right position, i've checked hundreds of times), but for some reason it gets flattened on the y plane (Vertically). It looks like i can't extend my mesh's triagles further from the vector z of my trasform position. My project is set to 2D, but i tried to make a new 3D project to see if that was the problem. It wasn't. What did i get wrong? Here's some images, probably you'll understand better.

Here's what i get:

Here's what the mesh should look like(i've got 20 triangles and 12 vertices, the right number: Maybe the normals are a bit messed up):

Here's the script:

     private void generateMesh(Material standard)
     {
 
         MeshRenderer hexRend = gameObject.AddComponent<MeshRenderer>();
         MeshFilter hexFilt = gameObject.AddComponent<MeshFilter>();
         Mesh hexMesh = hexFilt.mesh;
 
         MeshCollider hexCol = gameObject.AddComponent<MeshCollider>();
         hexCol.convex = true;
 
         Rigidbody meshRig = gameObject.AddComponent<Rigidbody>();
         meshRig.isKinematic = true;
 
 
 
         hexRend.material = standardMaterial;
 
         hexMesh.Clear(); hexMesh.ClearBlendShapes();
 
 
 
         float scale = transform.localScale.x;
         float xxx = scale + (scale / 1.4f);
 
         Vector3[] corners = new Vector3[12];
 
         // lato alto dell'esagono
 
         corners[1] = new Vector3(scale, 0);
         corners[2] = new Vector3(scale + (scale / 2), xxx / 2);
         corners[3] = new Vector3(scale, xxx);
         corners[4] = new Vector3(0, xxx);
         corners[5] = new Vector3(-(scale / 2), xxx / 2);
         
         for (int x = 6; x < corners.Length; x++)
         {
             corners[x] = corners[x - 6];
 
             corners[x] += new Vector3(0, 0, scale);
         }
 
 
         hexMesh.vertices = corners;
 
         hexMesh.triangles = new int[]
         {
             0, 4, 5,
             0, 3, 4,
             0, 1, 3,
             1, 2, 3,
 
 
             0, 6, 1,
             1, 6, 7,
 
             1, 2, 7,
             2, 7, 8,
 
             2, 3, 8,
             3, 8, 9,
 
             3, 9, 10,
             3, 4, 10,
 
             4, 10, 11,
             4, 5, 11,
 
             0, 5, 6,
             5, 6, 11,
 
 
             6, 10, 11,
             6, 9, 10,
             6, 7, 9,
             7, 8, 9
         };
 
         hexMesh.RecalculateNormals();
     }

I've tried to re-write the script completely so the hexagon get generated on the z plane, instead of the y plane, but it get flattened out on the z plane (So horizontally, instead of vertically; My hexagon got generated, but 2D on the z plane): I've tried to create a new unity project, to see if maybe i messed something up: I've tried to rotate the vertices, to they face the camera: I've tried to attach the script to a primitive 3D object, to see if maybe was the trasform of a new empty object (just because the project is set to 2D) to flatten the mesh: But nothing worked. I don't know what to do anymore. Please... Help. Thanks in advance.

btw i'm not an english native.