Could you please try with the following patch:

Index: ContextMenu.cpp

--- ContextMenu.cpp (revision 11643)
+++ ContextMenu.cpp (working copy)
@@ -159,14 +159,6 @@
// Set node parent
ParentClass::SetNodeParent(parent);

• // Update context menu placement

• CoerceValue<bool>(HasDropShadowProperty);

• CoerceValue<float>(HorizontalOffsetProperty);

• CoerceValue<PlacementMode>(PlacementProperty);

• CoerceValue<Rect>(PlacementRectangleProperty);

• CoerceValue<Ptr<UIElement>>(PlacementTargetProperty);

• CoerceValue<float>(VerticalOffsetProperty);

•  // Notify menu items
   MenuItem::SetIsInsideContextMenu(this, parent != 0);

  }
  @@ -418,7 +410,13 @@
  mPopupInternal->SetChild(this);
  mPopupInternal->Bind(this);

• // Update context menu placement

• CoerceValue<bool>(HasDropShadowProperty);

• CoerceValue<float>(HorizontalOffsetProperty);

• CoerceValue<PlacementMode>(PlacementProperty);

• CoerceValue<Rect>(PlacementRectangleProperty);
  CoerceValue<Ptr<UIElement>>(PlacementTargetProperty);

• CoerceValue<float>(VerticalOffsetProperty);

   Mouse* mouse = GetMouse();
   mMenuCapture = DynamicCast<Menu*>(mouse->GetCaptured());</pre>

Hello, did you find time to try the mentioned patch? We want to include this in the following 3.1.6 release that is coming by the end of this week.