SwiftData not persisted across runs on document-based app

Hello! I have followed steps outlined in Build an app with SwiftData to create a document-based app to create and save a set of flashcards. I have defined by model as follows:

@Model
final class Card {
    var createdAt: Date
    var front: String
    var back: String
    
    init(front: String, back: String, createdAt: Date = .now) {
        self.createdAt = createdAt
        self.front = front
        self.back = back
    }
}

I am loading a document group as described in the video:

@main
struct DeckApp: App {
    var body: some Scene {
        #if os(iOS) || os(macOS)
        DocumentGroup(editing: Card.self, contentType: .deck) {
            ContentView()
        }
        #else
        WindowGroup {
            ContentView()
                .modelContainer(for: Card.self)
        }
        #endif
    }
}

Moreover, I have defined document and exported types in info.plist:

However, when I try to open a previously saved document, the items do not show up in the app, even though I can see some relevant strings in StoreContent-wal. Would anyone please be able to point me to something I must have missed? Thank you in advance.