SwiftUI onDrag not showing preview image when running on device

I've been struggling with drag and drop as a beginner. Why does your snippet above produce a warning Result of call to loadObject(ofClass:completionhandler:) is unused? And why would the result print, but when used to update a variable in view produce an error about immutable self?

Code Block swift
import SwiftUI
struct DragNDrop: View {
		@State var isDropTarget = false
		var displayThisNumber: Int = 0
		var body: some View {
				VStack{
						Text(String(displayThisNumber))
						ZStack {
								Image(systemName: "5.circle.fill")
								Circle()
						}
								.font(.system(size: 40))
								.onDrag { return NSItemProvider(object: String(Int(5)) as NSString) }
						Color.orange
								.opacity(isDropTarget ? 0.5 : 1)
								.onDrop(of: ["public.text"], isTargeted: $isDropTarget) { items in
										for item in items {
												if item.canLoadObject(ofClass: NSString.self) {
														item.loadObject(ofClass: String.self) { str, _ in
																guard str != nil else { return }
																displayThisNumber += Int(str)
														}
												}
												return true
										}
								}
				}
		}
}

Thanks for your comment. The loadObject function of the NSItemProvider returns a Progress element which you can use to display a progress to the user while the item is loaded. I skipped that in this example.
Your code crashes, because you need to declare your variable as a @State var, when the variable affects swiftui code and you want to change it in runtime.

Coming back to my initial question, do you also have the issue, that you see the image if you drag running the simulator, but when running on a real device, you only see a transparent rect as preview image?

Also struggling with Drag-n-Drop in SwiftUI within an app. If you find an answer to this, please post it. I'll be posting other related questions about my specific issue.