I have a WPF code in which I can not get notified property updates.
My code needs to have such structure:

A1… An (view .xaml & .xaml.cs) → B1… Bn (viewmodel .cs)
C (model .cs, my business logic)
D (utility .cs like constants etc)
E (custom object .cs, that will be x-times instantiated in my model C)

Diagram: https://drive.google.com/open?id=1vJGglH4DxipEUQSfHl47_gfkxUmr9NAe


What I need is that ONLY my custom object implements the InotifyPropertyChanged, and NOT my viewmodels, but I couldn’t get the Gui notified when settig the properties of my custom objects (E) inside my models (C).
Here is an example of what I have so far:

In my views .xaml:

<Button 
    Content="{Binding content, Mode=OneWay, NotifyOnTargetUpdated=True}"
    Command="{Binding action}" />

In my views .xaml.cs (code behind):

public A1()
{
    InitializeComponent();
    DataContext = new B1();
}

In my viewmodels .cs:

public class B1 : C
{
    public string content => MyObject.Text;
    public ICommand action => MyObject.Pressed;
}

In my models .cs:

public class C : D
{
    // here i instantiate my object(s) 
    public E MyObject = new E();

    // here comes my stuff
    ... 
}

public class D
{
    //my constants and wrappers
    ... 
}

And for my custom objects (they will be x-times instantiated in my model):

public class E : INotifyPropertyChanged
{
    private string _text = String.Empty;
    public string Text
    {
        get => _text
        set => SetProperty(ref _text, value);
    }

    private readonly _DelegateCommand _pressed;
    public ICommand Pressed => _pressed;

    private void OnPressed(object commandParameter, string value)
    {
        Text = "newtext";
        _pressed.InvokeCanExecuteChanged();
    }

    private bool CanExecute(object commandParameter)
    {
        ... // some logic here
    }

    public E()
    {
        _pressed = new _DelegateCommand(OnPressed, CanExecute);
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public bool SetProperty<T>(ref T field, T newValue, [CallerMemberName]string propertyName = null)
    {
        if (!EqualityComparer<T>.Default.Equals(field, newValue))
        {
            field = newValue;
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
            return true;
        }
        return false;
    }
}

Can anyone help me please on this?
Thanks a lot in advance for any hints!
(PS: Ihr könnt mich gerne auch auf deutsch beantworten!)