My SwiftUI app renders a SCNScene with the code below. The scene displays visible nodes that can be tapped to show an info.
When a tap to a node ends, hitTest of the renderer (saved in the viewModel) is called. It returns the tapped node and sets isShowingVehicleInfo so that the MainView shows the VehicleInfoView above the Board3DView.

This works, but only the 1st time.
When the same node is tapped a 2nd time, hitTest no longer finds the node.
If however, another mode is tapped, hitTest finds the other node, but also only once.

I have a slightly modified code that behaves correctly, i.e. finds nodes always.
Instead of using ZStack to display the node info, it uses a sheet.

I prefer the ZStack version, because it allows me to control the info size, whereas the sheet version always presents a full size info.

I don’t understand why the ZStack version has this strange behavior to find a node only once.
Any help is welcome!

First code using ZStack that finds a node only once:

struct MainView: View {
    @State private var isShowingVehicleInfo = false
    // …

    var body: some View {
        NavigationStack { // Required for a toolbar in iOS
            VStack {
                TitleAndToolbarView(isShowingVehicleTypeInfo: $isShowingVehicleTypeInfo, 
                                    isShowingVehicleInfo: $isShowingVehicleInfo, 
                                    viewModel: viewModel)
                .padding(.top)
                
                ZStack {
                    GeometryReader { geometry in
                        Board3DView(viewModel: viewModel)
                            .onChange(of: geometry.size) {
                                viewModel.setMainViewSize(geometry.size)
                            }
                            .onChange(of: viewModel.selectedVehicle, {
                                if viewModel.selectedVehicle != nil {
                                    isShowingVehicleInfo = true
                                }
                            })
                            .edgesIgnoringSafeArea(.all)
                    } // geo reader
                    .padding(.top)
                    
                    if isShowingVehicleInfo {
                        VehicleInfoView(isShowingVehicleInfo: $isShowingVehicleInfo, 
                                        isShowingCameraFullScale: $isShowingCameraFullScale, 
                                        viewModel: viewModel)
                        .background(.white)
                    }
                }
            }
        }
    }
}

struct Board3DView: View {
    // …

    var body: some View {
        
        // Define a spacial tap gesture
        let tapGesture: _EndedGesture<SpatialTapGesture> = SpatialTapGesture(count: 1)
            .onEnded() { event in
                // hit test
                guard let renderer = viewModel.renderer else { return }
                let hits = renderer.hitTest(event.location, options: [SCNHitTestOption.categoryBitMask: ~NodeType.cannotBeTapped.rawValue])
                if let firstHitResult = hits.first {
                    // Here, isShowingVehicleInfo is set in the MainView
                }
            }

        ZStack {
            Color.black.edgesIgnoringSafeArea(.all)
            
            SceneView (
                scene: viewModel.scene,
                options: [], // .allowsCameraControl is disabled
                delegate: viewModel
            )
            .simultaneousGesture( tapGesture )
            // …
        }
    }
}

Second code using sheet that finds the node always:

var body: some View {
    NavigationStack { // Required for a toolbar in iOS
        VStack {
            TitleAndToolbarView(isShowingVehicleTypeInfo: $isShowingVehicleTypeInfo, 
                                isShowingVehicleInfo: $isShowingVehicleInfo, 
                                viewModel: viewModel)
            .padding(.top)
            
            GeometryReader { geometry in
                Board3DView(viewModel: viewModel)
                    .onChange(of: geometry.size) {
                        viewModel.setMainViewSize(geometry.size)
                    }
                    .onChange(of: viewModel.selectedVehicle, {
                        if viewModel.selectedVehicle != nil {
                            isShowingVehicleInfo = true
                        }
                    })
                    .edgesIgnoringSafeArea(.all)
            } // geo reader
            .padding(.top)
            .sheet(isPresented: $isShowingVehicleInfo, onDismiss: {
                viewModel.deselectVehicle()
                isShowingVehicleInfo = false
            }) {
                VehicleInfoView(isShowingVehicleInfo: $isShowingVehicleInfo, 
                                isShowingCameraFullScale: $isShowingCameraFullScale, 
                                viewModel: viewModel)
            }
        }
    }
}

}