Wrapped UIActivityViewController is blank on first showing

Here's the entire app below. On iOS 15, it pops up blank. If you dismiss it and click "Share" again, then it looks right. Is this a bug, or is the code wrong?

struct ContentView: View {
    @State private var showShare = false
    @State private var shareItems: [Any] = []

    var body: some View {
        VStack {
            Text("Test ActivityViewController")
            Button("Share") {
                share()
            }.sheet(isPresented: $showShare) {
                print("dismissed")
            } content: {
                ActivityViewController(activityItems: shareItems)
            }
        }
    }
    func share() {
        shareItems = ["test"]
        showShare = true
    }
}

struct ActivityViewController: UIViewControllerRepresentable {
    let activityItems: [Any]
    func makeUIViewController(context: Context) -> UIActivityViewController {
        let c = UIActivityViewController(activityItems: activityItems, applicationActivities: nil)
        return c
    }

    func updateUIViewController(_ uiViewController: UIActivityViewController, context: Context) {}
}