View is not refreshing

Question

here I have two classes. When I add a Person the view updates, but when I add a TodolistItem, the view isn't updating. When I press the Button for adding a todo and then press the button for adding a person, the person and the todo is there. So the button works properly, the only problem is the refresh of my view.

That's my code:

import SwiftUI

class Person: Identifiable, ObservableObject {
    let id = UUID()
    @Published var name: String
    @Published var item: [TodolistItem]
    
    init(name: String, item: [TodolistItem]) {
        self.name = name
        self.item = item
    }
}

class TodolistItem: Identifiable, ObservableObject {
    @Published var todoName: String
    @Published var priority: String
    
    init(todoName: String, priority: String) {
        self.todoName = todoName
        self.priority = priority
    }
}

struct Todolist: View {
    
    @State private var personen: [Person] = [
    Person(name: "Michi", item: [
        TodolistItem(todoName: "Reifenwechsel", priority: "Niedrig"),
        TodolistItem(todoName: "Irgendwas", priority: "Mittel")
    ]),
    Person(name: "Tina", item: [
        TodolistItem(todoName: "Haushalt", priority: "Dringend!")
    ])
    ]
    
    let navTitle: String
    
    var body: some View {
        
        NavigationStack {
            List {
                ForEach(personen) { person in
                    Section(person.name) {
                        ForEach(person.item) { item in
                            SubView(item: item)
                        }
                        .onDelete { offSet in
                            person.item.remove(atOffsets: offSet)
                        }
                        
                        Button {
                            let newItem = TodolistItem(todoName: "Opfer", priority: "Dringend!!")
                            withAnimation {
                                person.item.append(newItem)
                                person.objectWillChange.send()
                            }
                        } label: {
                            HStack {
                                Image(systemName: "plus")
                                Text("Neues Todo hinzufügen")
                            }
                        }
                        
                    }
                }
            }
            .listStyle(.insetGrouped)
        }
        .navigationTitle(navTitle)
        .navigationBarItems(trailing:
                                Button(action: { addItem() }, label: {
            Image(systemName: "plus.circle")
        })
        )
    }
    
    func addItem() {
        let newItem = Person(name: "Test", item: [TodolistItem(todoName: "Test1", priority: "Niedrig")])
        personen.append(newItem)
    }
}

struct SubView: View {
    
    @State private var isDone: Bool = false
    @ObservedObject var item: TodolistItem
    
    var body: some View {
        VStack {
            HStack {
                Text(item.todoName)
                Spacer()
                Text(item.priority)
                    .padding(.horizontal)
                
                Button(action: {
                    isDone.toggle()
                }, label: {
                    Image(systemName: isDone ? "checkmark.circle.fill" : "checkmark.circle")
                })
            }
        }
    }
}

Maybe its just a small Mistake, but I'm not getting it.