I believe a recent fix has caused sub menus to fail to show in ContextMenus.

To reproduce run the test class below:

1. Right cick on the label and mouse over the sub menu to display it.

2. Click on the Rebuild button.

3. Repeat step 1.

********************************************* Test Class **********************************************
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ContextMenu;
import javafx.scene.control.Label;
import javafx.scene.control.Menu;
import javafx.scene.control.MenuItem;
import javafx.scene.layout.Region;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class ContextMenuTest extends Application {

   @Override public void start(final Stage primaryStage) throws Exception {

      primaryStage.centerOnScreen();
      primaryStage.setHeight(350);
      primaryStage.setWidth(500);
      final Menu submenu = new Menu("Sub Menu");
      submenu.getItems().add(new MenuItem("Test 1"));
        
      Label contextMenuLabel = new Label("Right Click On Me!");
      final ContextMenu contextMenu = new ContextMenu(submenu);
      contextMenuLabel.setContextMenu(contextMenu);
       
      Button button = new Button("Rebuild Menu");
      button.setOnAction(new EventHandler<ActionEvent>() {
         @Override public void handle(ActionEvent event) {
            contextMenu.getItems().clear();
            contextMenu.getItems().add(submenu);
         }
      });
      VBox box = new VBox(20, contextMenuLabel, button);
      box.setMaxSize(Region.USE_PREF_SIZE, Region.USE_PREF_SIZE);
       
      primaryStage.setScene( new Scene( new StackPane( box ) ) );

      primaryStage.show();

   }
    
   public static void main(String[] args) throws Exception {
      launch(args);
   }

}