DataGridCell Binded value update upon row selection change

Question

My propblem is that DataGrid sends new value set by user with GUI only when the selected line is changed. When I modify value in form and press "Enter" to confirm input, everything works fine (because "Enter" moves selection to next line). But when I modify value in cell and press with mouse to any other cell in current row, new value is assigned to cell but not sent to binded object. In debugger I see that converter's ConvertBack method is called but Field.Value property setter is not! Field.Value property setter breakpoint fires only after row selection change. How can I force my Model object value change after cell edit finish, not row selection changed?

DataGrid's style:

<Style x:Key="ElementDataGridStyle" TargetType="DataGrid">
    <Setter Property="AutoGenerateColumns" Value="False"/>
    <Setter Property="HeadersVisibility" Value="Column"/>
    <Setter Property="SelectionUnit" Value="Cell"/>
    <Setter Property="CellStyle">
        <Setter.Value>
            <Style TargetType="DataGridCell">               
                <Style.Triggers>
                    <Trigger Property="IsReadOnly" Value="true">
                        <Setter Property="Background" Value="LightGray"/>
                    </Trigger>                  
                </Style.Triggers>
                <EventSetter Event="Loaded" Handler="ElementDataGridStyleCellStyle_Loaded"/>
            </Style>
        </Setter.Value>
    </Setter>   
</Style>

Code that binds DataGrid to my Model

private void SetDataGridContent(DataGrid grid, Core.Item.ItemCollection collection)
{
    grid.Columns.Clear();            
    if (collection != null)
    {                       
        for (int i = 0; i < collection.FieldProps.Count; i++)
        {
            Core.FieldProp prop = collection.FieldProps[i];
            if (prop.VisualName != null)
            {               
                MultiBinding multiBinding = new MultiBinding()
                {
                    Converter = new Visual.FieldValueConverter()
                };
                multiBinding.Bindings.Add(new Binding($"Fields[{i}]"));
                multiBinding.Bindings.Add(new Binding($"Fields[{i}].Value"));
                DataGridTextColumn column = new DataGridTextColumn
                {
                    Binding = multiBinding,
                    Header = prop.VisualName,
                    IsReadOnly = !prop.UIEditable,                            
                };              
                SetColumnFieldIndex(column, i);                             
                grid.Columns.Add(column);                        
            }                    
        }       
    }
    grid.ItemsSource = collection;            
}

Fields - is ObservableCollection successor

sealed class FieldCollection : ObservableCollection<Field>

Field class implements INotifyPropertyChanged interface

public class Field : INotifyPropertyChanged
{
    private string _value;

    public string Value
    {
        get => _value;
        set
        {
            if (_value != value)
            {
                Modify(value);
                NotifyPropertyChanged();
            }
        }
    }

    private void Modify(string value)
    {
        _value = value;
    }

    protected void NotifyPropertyChanged([CallerMemberName]string propertyName = null)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

Value converter looks like this:

class FieldValueConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        return values[1];
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        object[] result = new object[2];
        result[0] = Binding.DoNothing; //DependencyProperty.UnsetValue;
        result[1] = value;
        return result;
    }
}