.NET C# Java Javascript Exception

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:

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

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

public A1()
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";

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!)