NavigationSplitView No Toggle Button

I went back to square one since the NavigationLink isActive is deprecated, this is when I found out about NavigationSplitView which removes the hassle of creating a 2 column app.

However, I can never figure out why the toggle button does not show. I copied this sample code (already tried 2 tutorials, copy pasted them but still no toggle button)

Anyone know why?

import SwiftUI

enum DemoScreen: String, Codable {
  case first, second, third

  var title: String {
    rawValue.capitalized
  }
}

struct ContentView: View {

  @State
  private var selection: DemoScreen? = .first

  var body: some View {
    NavigationSplitView {
      sidebarContent
    } detail: {
      detailContent
    }
  }
}

extension ContentView {

  var sidebarContent: some View {
    List {
      link(to: .first)
      link(to: .second)
      link(to: .third)
    }
  }

  func link(to page: DemoScreen) -> some View {
    NavigationLink(value: page) {
      Text(page.title)
    }
  }
}

extension ContentView {

  @ViewBuilder
  var detailContent: some View {
    if let selection = selection {
      detailContent(for: selection)
        .buttonStyle(.bordered)
    } else {
      Text("No selection")
    }
  }

  @ViewBuilder
  func detailContent(for screen: DemoScreen) -> some View {
    switch screen {
    case .first: Button("First button") {}
    case .second: Button("Second button") {}
    case .third: Button("Second button") {}
    }
  }
}

Why is there no toggle button above? And why is the menu always showing? I cant see the detiail view anymore