Why does my split function keep creating "Error reading characters of string"?

Question

Can someone tell me why when my split function runs it makes the list2 of the object lst2 read "Error reading characters of string"

LinkedDeque* LinkedDeque::split()
{
    LinkedDeque* lst2 = new LinkedDeque();
    DLinkedList list2 = *(D.split());
    lst2->list2 = list2;
    return lst2;
}
void LinkedDeque::print() {
    
    D.print();
}
void LinkedDeque::splitprint() {
    list2.print();
}

int main()
{
    LinkedDeque list;
    while (true)
    {
        string x;
        cout << "Enter a non-negative number (Negative number to end): ";
        cin >> x;
        cout << endl;
        if (stoi(x) < 0)
            break;
        list.insertFront(x);
    }

    cout << "Entries Given:\n";
    list.print();

    cout << "Splitting the given list ...\n";
    LinkedDeque lst2 = *(list.split());
    
    cout << "\n1st Split List : \n";
    list.print();
    cout << "2nd Split List : \n";
    lst2.splitprint();

    return EXIT_SUCCESS;

}

If more code is needed to tell me why this is going on I can provide the full code of the program I am working on. I am clearly not the best at programing so please explain it so I can understand. I have been working on this for 3 days now and cannot figure out why this is happening.