CombineMeshes result invisible.

I am fairly new to Unity, and testing CombineMeshes. In my previous projects in other engines, I made a similar system of my own, which was critical to most of the games I made!

I can create a single mesh via the CreateMesh, plug it straight into the filter's mesh property, and it works great. But if I use CombineMeshes, nothing is visible. Stranger yet, if I print the index buffer (triangles in Unity) or vertex buffer, everything looks dandy. What am I missing?

Entire sample below!

 private GameObject test;

 // Use this for initialization
 void Start () 
 {
     test = new GameObject();
     MeshFilter filter = test.AddComponent<MeshFilter>();
     Renderer renderer = test.AddComponent<MeshRenderer>();
     renderer.material.color = Color.white;

     int count = 1;
     CombineInstance[] combines = new CombineInstance[count];
     for (int i = 0; i < count; ++i)
     {
         combines[i].mesh = CreateMesh();
         combines[i].transform = Matrix4x4.identity; //Matrix4x4.TRS(Vector3.up * i, Quaternion.identity, Vector3.one);
     }

     filter.mesh = new Mesh(); //CreateMesh();
     filter.mesh.CombineMeshes(combines);
     Debug.Log(filter.mesh.triangles.Length);
     Debug.Log(filter.mesh.vertices);
 }
 
 // Update is called once per frame
 void Update () 
 {
     test.transform.Rotate(gameObject.transform.rotation.eulerAngles + new Vector3(0f, 1f, 0f));
 }

 private Mesh CreateMesh()
 {
     Vector3[] vertices = new Vector3[4];
     Vector3[] normals = new Vector3[4];
     Vector2[] uvs = new Vector2[4];
     Vector4[] tangents = new Vector4[4];

     vertices[0] = new Vector3(-0.5f, -0.5f, 0.5f);
     normals[0] = Vector3.forward;
     vertices[1] = new Vector3(0.5f, -0.5f, 0.5f);
     normals[1] = Vector3.forward;
     vertices[2] = new Vector3(-0.5f, 0.5f, 0.5f);
     normals[2] = Vector3.forward;
     vertices[3] = new Vector3(0.5f, 0.5f, 0.5f);
     normals[3] = Vector3.forward;

     int[] indices = new int[6];
     indices[0] = 0;
     indices[1] = 1;
     indices[2] = 2;
     indices[3] = 2;
     indices[4] = 1;
     indices[5] = 3;

     BuildTangentSpaceDataForTriangleList(indices, vertices, uvs, tangents);

     Mesh mesh = new Mesh();
     mesh.Clear();
     mesh.vertices = vertices;
     mesh.uv = uvs;
     mesh.triangles = indices;
     mesh.normals = normals;
     mesh.tangents = tangents;

     return mesh;
 }