CommandBuffer.CopyTexture with mipmaps?

Hey all! I'm trying to copy a texture from a temporary render texture in a command buffer to the final texture I want to use. Here's the code:

Code (CSharp):

1.             // draw a bunch of leaves on the leaves texture
2.             int bigTexSize = 256;
3.             leavesTexture = new Texture2D(bigTexSize, bigTexSize, TextureFormat.R8, false, false);
4.             CommandBuffer cb = new CommandBuffer();
5.             int rt = Shader.PropertyToID("rt");
6.             RenderTextureDescriptor desc = new RenderTextureDescriptor();
7.             desc.width = desc.height = bigTexSize;
8.             desc.autoGenerateMips = false;
9.             desc.colorFormat = RenderTextureFormat.R8;
10.             desc.useMipMap = false;
11.             desc.msaaSamples = 1;
12.             desc.dimension = TextureDimension.Tex2D;
13.             desc.depthBufferBits = 0;
14.             desc.shadowSamplingMode = ShadowSamplingMode.None;
15.             desc.volumeDepth = 1;
16.             //RenderTexture rt2 = new RenderTexture(desc);
17.             cb.GetTemporaryRT(rt, desc);
18.             cb.SetRenderTarget(rt);
19.             cb.ClearRenderTarget(true, true, Color.black, 0);
20.             cb.SetViewProjectionMatrices(Matrix4x4.identity, Matrix4x4.Ortho(0, bigTexSize, 0, bigTexSize, 0, bigTexSize));
21.             float leafMass = result.leafMass * result.leafLength * result.leafLength; // average about 7500*4*4 = 120,000
22.             int instances = Mathf.Clamp(Mathf.FloorToInt(1000000.0f/leafMass), 1, 1000);
23.             Material material = new Material(Shader.Find("Unlit/LeafDrawing"));
24.             material.mainTexture = leafTexture;
25.             for (int i = 0; i < instances; i++)
26.             {
27.                 float angle = Random.Range(0, 360);
28.                 cb.DrawMesh(leafDrawingMesh, Matrix4x4.TRS(new Vector3(Random.Range(64,bigTexSize-64),Random.Range(64,bigTexSize-64), -bigTexSize/2), Quaternion.AngleAxis(angle, Vector3.forward), Vector3.one * Random.Range(0.9f, 1.3f) * result.leafLength * 5),material, 0);
29.             }
30.             for (int i = 0; i < leavesTexture.mipmapCount; i++)
31.                 cb.CopyTexture(rt, 0, i, leavesTexture, 0, i);
32.             cb.ReleaseTemporaryRT(rt);
33.             Graphics.ExecuteCommandBuffer(cb);
34.             Destroy(material);

Now, this code works fine. But if you set the Texture2D to have mip maps, and the render texture to have mips, the result is just black.

What am I doing wrong here? Anyone know?

 

Found out why it doesn't work:

 

(well, that doesn't explain why it works when there are no mipmaps involved)