Exception in RibbonGallery when Windows dpi value is 125% or greater

Question

I am using a RibbonGallery in my WPF application.

<r:RibbonGallery ItemsSource="{Binding MenuBar}"
             Style="{StaticResource GalleryStyle}">
</r:RibbonGallery> 

ViewModel:

public ObservableCollection<MenuCategoryModel> MenuBar { get; set; }

When I open the RibbonGallery and click one of the RibbonGalleryItems, the required screen is opened and the RibbonGallery is automatically closed. But in case if that specific screen is already opened, and I click the same RibbonGalleryItem again, the RibbonGallery will stay open.

To manually close the RibbonGallery, I reset the value of the ItemSource of RibbonGallery like this:

var tempMenuBar = MenuBar;
MenuBar = null;                                                                                         
OnPropertyChanged("MenuBar");
MenuBar = tempMenuBar;
OnPropertyChanged("MenuBar");

This successfully closes the RibbonGallery, but when the Windows dpi value is set to 125%, and the same RibbonGalleryItem is clicked (whose screen is already in focus), I get the following exception:

Value cannot be NULL. Parametername: menuSite in PresentationCore

This is the stack trace:

at System.Windows.Input.InputManager.PushMenuMode(PresentationSource menuSite) 
at System.Windows.Controls.Primitives.MenuBase.PushMenuMode(Boolean isAcquireFocusMenuMode) 
at System.Windows.Controls.Primitives.MenuBase.OnPreviewKeyboardInputProviderAcquireFocus(Object sender, KeyboardInputProviderAcquireFocusEventArgs e) 
at System.Windows.Input.KeyboardInputProviderAcquireFocusEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget) 
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target) 
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs) 
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised) 
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args) 
at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args) 
at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted) 
at System.Windows.Input.InputManager.ProcessStagingArea() 
at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input) 
at System.Windows.Input.KeyboardDevice.TryChangeFocus(DependencyObject newFocus, IKeyboardInputProvider keyboardInputProvider, Boolean askOld, Boolean askNew, Boolean forceToNullIfFailed) 
at System.Windows.Input.KeyboardDevice.Focus(DependencyObject focus, Boolean askOld, Boolean askNew, Boolean forceToNullIfFailed) 
at System.Windows.Input.KeyboardDevice.Focus(IInputElement element) 
at System.Windows.UIElement.Focus() 
at Microsoft.Windows.Controls.Ribbon.RibbonGalleryItem.OnMouseMove(MouseEventArgs e) 
at System.Windows.UIElement.OnMouseMoveThunk(Object sender, MouseEventArgs e) 
at System.Windows.Input.MouseEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget) 
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target) 
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs) 
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised) 
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args) 
at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args) 
at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted) 
at System.Windows.Input.InputManager.ProcessStagingArea() 
at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input) 
at System.Windows.Input.MouseDevice.Synchronize() 
at System.Windows.Input.MouseDevice.ChangeMouseCapture(IInputElement mouseCapture, IMouseInputProvider providerCapture, CaptureMode captureMode, Int32 timestamp) 
at System.Windows.Input.MouseDevice.PreNotifyInput(Object sender, NotifyInputEventArgs e) 
at System.Windows.Input.InputManager.ProcessStagingArea() 
at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input) 
at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport) 
at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel) 
at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled) 
at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) 
at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) 
at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) 
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) 
at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)

This problem occurs only when Windows dpi value is 125% or more.

Also, this cannot be reproduced in debug mode.

Any ideas on what is the actual cause of this exception and any suggestions on how to fix this?