NavigationSplitView no longer pops back to the root view when selection = nil in iOS 26.4 (with a nested TabView)

In iOS 26.4 (iPhone, not iPad), when a NavigationSplitView is combined with a nested TabView, it no longer pops back to the root sidebar view when the List selection is set to nil. This has been working fine for at least a few years, but has just stopped working in iOS 26.4.

Here's a minimal working example:

import SwiftUI

struct ContentView: View {
    @State var articles: [Article] = [Article(articleTitle: "Dog"), Article(articleTitle: "Cat"), Article(articleTitle: "Mouse")]
    @State private var selectedArticle: Article? = nil
    
    var body: some View {
        NavigationSplitView {
            TabView {
                Tab {
                    List(articles, selection: $selectedArticle) { article in
                        Button {
                            selectedArticle = article
                        } label: {
                            Text(article.title)
                        }
                    }
                } label: {
                    Label("Explore", systemImage: "binoculars")
                }
            }
        } detail: {
            Group {
                if let selectedArticle {
                    Text(selectedArticle.title)
                } else {
                    Text("No selected article")
                }
            }
            .navigationBarBackButtonHidden(true)
            .toolbar {
                ToolbarItem(placement: .topBarTrailing) {
                    Button("Close", systemImage: "xmark") {
                        selectedArticle = nil
                    }
                }
            }
        }
    }
}

struct Article: Identifiable, Hashable {
    let id: String
    let title: String
    
    init(articleTitle: String) {
        self.id = articleTitle
        self.title = articleTitle
    }
}

First, I'm aware that nesting a TabView inside a NavigationSplitView is frowned upon: Apple seems to prefer NavigationSplitView nested inside a Tab. However, for my app, that leads to a very confusing user experience. Users quickly get lost because they end up with different articles open in different tabs and it doesn't align well with my core distinction between two "modes": article selection mode and article reading mode. When the user is in article selection mode (sidebar view), they can pick between different ways of selecting an article (Explore, Bookmarks, History, Search), which are implemented as "tabs". When they pick an article from any tab they jump into article reading mode (the detail view).

Second, I'm using .navigationBarBackButtonHidden(true) to remove the auto back button that pops back to the sidebar view. This button does still work in iOS 26.4, even with the nested TabView. However, I can't use the auto back button because my detail view is actually a WebView with its own back/forward logic and UI. Therefore, I need a separate close button to exit from the detail view. My close button sets selectedArticle to nil, which (pre-iOS 26.4) would trigger the NavigationSplitView to pop back to the sidebar view.

For some reason, in iOS 26.4 the NavigationSplitView doesn't seem to bind correctly to the List's selection parameter, specifically when there's a TabView nested between them. Or, rather, it binds, but fails to pop back when selection becomes nil.

One option is to replace NavigationSplitView with NavigationStack (on iPhone). NavigationStack still works with a nested TabView, but it creates other downstream issues for me (as well as forcing me to branch for iPhone and iPad), so I'd prefer to continue using NavigationSplitView.

Does anyone have any ideas about how to work around this problem? Is there some way of explicitly telling NavigationSplitView to pop back to the sidebar view on iPhone? (I've tried setting the column visibility but nothing seems to work).

Thanks for any help!