Don't understand coordinate conversion of visionOS RealityKit

I want to convert a world coordinate to the local coordinate of a RealityKit entity. According to the docs, this should be possible using convert(position:from:), called on the entity. Since it did not work as expected, I wrote a little test project. I used Apple's template for a visionOS immersive app, and modified it slightly. This is my immersive view:

struct ImmersiveView: View {
    var body: some View {
        RealityView { content in
            var defaultMaterial = UnlitMaterial()
            defaultMaterial.color.tint = .brown
            let mesh = MeshResource.generateBox(size: 1)
            let boxEntity = ModelEntity(mesh: mesh, materials: [defaultMaterial])
            let anchorEntity = AnchorEntity(world: SIMD3<Float>(0, 0, -4))
            anchorEntity.addChild(boxEntity)
            content.add(anchorEntity)
            
            let coordinate = SIMD3<Float>(0.1, 0.2, 0.3)
            let coordinateFrom = boxEntity.convert(position: coordinate, from: nil)
            let coordinateTo = boxEntity.convert(position: coordinate, to: nil)
            print("coordinateFrom: \(coordinateFrom)")
            print("coordinateTo: \(coordinateTo)")
        }
    }
}

It contains a box visible in front of the main window. The box is not at the origin (z = -4).

Unexpectedly, coordinateFrom as well as coordinateTo are equal to coordinate. I expected that coordinateFrom is different, because the box is not at the origin.
What am I missing?

A friend of mine found a solution:
Apparently, a view has to be rendered, before the coordinate conversion functions work.
Here is the extended code that demonstrates the conversion:

struct ImmersiveView: View {
    @State private var coordinateFrom = SIMD3<Float>(0, 0, 0)
    @State private var coordinateTo = SIMD3<Float>(0, 0, 0)
    @State private var anchorPosition = SIMD3<Float>(0, 0.0, -4)

    var body: some View {
      ZStack {
          RealityView { content in
              var defaultMaterial = UnlitMaterial()
              defaultMaterial.color.tint = .brown
              let mesh = MeshResource.generateBox(size: 1)
              let boxEntity = ModelEntity(mesh: mesh, materials: [defaultMaterial])
              boxEntity.name = "box"
              let anchorEntity = AnchorEntity(world: anchorPosition)
              anchorEntity.name = "anchor"
              anchorEntity.addChild(boxEntity)
              content.add(anchorEntity)

              print("---- not yet rendered coords")
              updateCoordinates(boxEntity: boxEntity)
          }
          update: { content in
              if let anchorEntity = content.entities.first?.findEntity(named: "anchor") as? AnchorEntity {
                  anchorEntity.setPosition(anchorPosition, relativeTo: nil)
              }
              if let boxEntity = content.entities.first?.findEntity(named: "box") as? ModelEntity {
                  updateCoordinates(boxEntity: boxEntity)
              }
          }
          VStack {
              Text("Coordinate From: \(coordinateString(coordinateFrom))")
              Text("Coordinate To: \(coordinateString(coordinateTo))")
              Button(action: {
                  anchorPosition += SIMD3<Float>(Float.random(in: -1..<1), 0, 0)
              }, label: { Text("Move") })
          }
          .padding()
          .background(Color.black.opacity(0.5))
          .cornerRadius(10)
          .foregroundColor(.white)
      }
    }
    private func updateCoordinates(boxEntity: ModelEntity) {
        let coordinate = SIMD3<Float>(0.1, 0.2, 0.3)
        let coordinateFrom = boxEntity.convert(position: coordinate, from: nil)
        let coordinateTo = boxEntity.convert(position: coordinate, to: nil)
        DispatchQueue.main.async {
            self.coordinateFrom = coordinateFrom
            self.coordinateTo = coordinateTo
        }
        print("coordinateFrom: \(coordinateFrom)")
        print("coordinateTo: \(coordinateTo)")
    }
    private func coordinateString(_ coordinate: SIMD3<Float>) -> String {
        String(format: "(%.2f, %.2f, %.2f)", coordinate.x, coordinate.y, coordinate.z)
    }
}