Reading Native Surface Texture into Streaming Unity Texture [Android]?

I am trying to retrieve the camera preview image on Android and show it on a plane in Unity. In my native code I created the following function:

 SurfaceTexture surfaceTex;
 
 public void setUpVideoTexture(int texturePtr){
     surfaceTex = new SurfaceTexture(texturePtr);
     surfaceTex.setOnFrameAvailableListener(this);
 
     Camera cam = Camera.open();//Alternatively I call this function on startup
     try {
         cam.setPreviewTexture(surfaceTex);
         cam.setPreviewCallback(this);
         cam.startPreview();
         Log.d("Unity","Preview texture set up");
     } catch (IOException e) {
         e.printStackTrace();
     }
 }

In Unity I call this function and pass the native texture pointer of the Unity texture:

 jo.Call("setUpVideoTexture", (int)renderer.material.mainTexture.GetNativeTexturePtr());

So now the camera preview image should be written into the Unity texture on every update.

However, on updating the surface texture, I get the error message "Error binding external texture image". I also tried using a RenderTexture but although I don't get an error the texture stays black. Why doesn't this work? Is it not possible to use the streaming texture in combination with a native surface texture?