Presenting content on Connected Display not working on iOS 27

I have an app that displays different content on a connected display (following this guide).

It's working fine on iOS 26 but no longer is working in iOS 27 (both dev betas) + the latest SDKs.

I tried to find any update notes but I couldn't find anything so I'm not sure if I'm doing something wrong or if it's an actual bug.

I was able to simplify it down to the simplest case here:

import SwiftUI

// App Delegate to setup the scene delegate
@main
class AppDelegate: UIResponder, UIApplicationDelegate {
    func application(_: UIApplication, didFinishLaunchingWithOptions _: [UIApplication.LaunchOptionsKey: Any]? = nil) -> Bool {
        print("Calling didFinishLaunchingWithOptions")
        return true
    }

    func application(_: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options _: UIScene.ConnectionOptions) -> UISceneConfiguration {
        print("Calling configurationForConnecting")
        let sceneConfig = UISceneConfiguration(name: nil, sessionRole: connectingSceneSession.role)
        sceneConfig.delegateClass = WindowSceneDelegate.self
        return sceneConfig
    }
}

// Scene delegate that sets up the view
class WindowSceneDelegate: UIResponder, UIWindowSceneDelegate {
    var window: UIWindow?

    func scene(_ scene: UIScene, willConnectTo _: UISceneSession, options _: UIScene.ConnectionOptions) {
        print("Calling scene(willConnectTo:) with role \(scene.session.role)")
        guard let windowScene = (scene as? UIWindowScene) else { return }
        let window = UIWindow(windowScene: windowScene)

        if scene.session.role == .windowExternalDisplayNonInteractive {
            window.rootViewController = UIHostingController(rootView: ExternalDisplay())
        } else {
            window.rootViewController = UIHostingController(rootView: ContentView())
        }

        self.window = window
        window.makeKeyAndVisible()
    }
}


struct ExternalDisplay: View {
    var body: some View {
        Text("Other World!")
    }
}

struct ContentView: View {
    var body: some View {
        Text("Hello, world!")
    }
}

I also have my Info showing "Enable Multiple Scenes" set to true.

I can screen mirror this app to my Mac (same result with an Apple TV).

On iOS 26, on my iPhone, I'd see "Hello World!" and on the connected display, I'd see "Other World!".

On iOS 27, this is no longer the case. On my connected display, I just see "Hello World".

I'm trying to figure out if I've missed something or if this is a dev beta bug.