Creating a new Core data Entry/Object while in modal view stops the dismissal of the view, presentationMode.wrappedValue.dismiss() no longer works.

Creating a new Core data Entry/Object (addItem) while in modal stops the dismissal of the view, presentationMode.wrappedValue.dismiss() no longer works. The sample below uses the template provided in Beta 6 with core data, with the additional of a full screen cover to save some data. After the new Item is created, the modal will no longer dismiss. Any way around this?

Code Block 
import SwiftUI
import CoreData
struct ContentView: View {
  @Environment(\.managedObjectContext) private var viewContext
  @FetchRequest(sortDescriptors: [NSSortDescriptor(keyPath: \Item.timestamp, ascending: true)],animation: .default) private var items: FetchedResults<Item>
  @State private var isPresented = false
  
  var body: some View {
    NavigationView {
      List {
        ForEach(items) { item in
          Text("\(item.timestamp!, formatter: itemFormatter)")
        }
        .onDelete(perform: deleteItems)
      }
      .toolbar {
        Button(action: {isPresented.toggle()}) {Image(systemName: "plus")}
          .fullScreenCover(isPresented: $isPresented, content: { PopUpView() })
      }
    }
  }
    private func deleteItems(offsets: IndexSet) {
        withAnimation {
            offsets.map { items[$0] }.forEach(viewContext.delete)
            do {
                try viewContext.save()
            } catch {
                let nsError = error as NSError
                fatalError("Unresolved error \(nsError), \(nsError.userInfo)")
            }
        }
    }
}
private let itemFormatter: DateFormatter = {
    let formatter = DateFormatter()
    formatter.dateStyle = .short
    formatter.timeStyle = .medium
    return formatter
}()
struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView().environment(\.managedObjectContext, PersistenceController.preview.container.viewContext)
    }
}
struct PopUpView: View {
  @Environment(\.managedObjectContext) private var viewContext
  @Environment(\.presentationMode) private var presentationMode
  var body: some View {
    Button(action: addItem) {Text ("Add Item")}
    Button(action: {presentationMode.wrappedValue.dismiss()} ) {Text ("Dismiss View")}
  }
  
  private func addItem() {
      let newItem = Item(context: viewContext)  
      newItem.timestamp = Date()
    do {
        try viewContext.save()
        self.presentationMode.wrappedValue.dismiss()
    } catch {
        let nsError = error as NSError
        fatalError("Unresolved error \(nsError), \(nsError.userInfo)")
    }
  }
}