Window gets closed while clicking on maximize button in Windows 8.1

I am facing an issue with RibbonControlsLibrary 3.5.40729.1 version. While clicking on maximize button, it is calling RibbonWindow_Closing(object sender, System.ComponentModel.CancelEventArgs e) function. As a result, the window gets closed. Also we can see the 'Close' tool tip menu on Maximize button.

This occurs only with Windows 8.1. I am attaching the xaml code with this. We are using RibbonControlsLibrary 3.5.40729.1 and Microsoft.Windows.Shell 3.5.40729.1 version.

Can any one please help me on this.

<ribbon:RibbonWindow x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:ribbon="http://schemas.microsoft.com/winfx/2006/xaml/presentation/ribbon" 
        xmlns:shell="http://schemas.microsoft.com/winfx/2006/xaml/presentation/shell"
        Title="Container" Height="600" Width="900"
        WindowStartupLocation="CenterScreen"
        Visibility="Visible" 
        AllowDrop="True"
        WindowStyle="SingleBorderWindow" WindowState="Normal" SizeToContent="Manual" ShowInTaskbar="True" ><ribbon:RibbonWindow.CommandBindings></ribbon:RibbonWindow.CommandBindings><Grid></Grid></ribbon:RibbonWindow>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using Microsoft.Windows.Controls.Ribbon;

namespace WpfApplication2
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : RibbonWindow
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }
}