Problem with Cursor WAIT binding and ComboBox

ComboSample.java

package sample;

import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.concurrent.Task;
import javafx.scene.Cursor;
import javafx.scene.Scene;
import javafx.scene.control.ComboBox;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * Steps to reproduce issues:
 * 1. Select "DEV" from first dropdown - it will run for 20s
 * 2. Immediately select "TEST" from 2nd dropdown - it will run for 5s
 * 
 * Expected result
 * 1. Cursor remains WAIT until both tasks have completed
 * 2. When both tasks have completed Cursor should remain at DEFAULT
 *    when placed over 2nd comboxbox drop down
 * 
 * Actual result
 * 1. Cursor changes to DEFAULT before 1st task has completed
 * 2. (Intermittent): After both tasks have completed, clicking on 2nd combo 
 *    and placing mouse pointer over dropdown list, causes cursor to change 
 *    back to WAIT.
 */
public class ComboSample extends Application {
    public static void main(String[] args) { launch(args); }

    private final ExecutorService pool = Executors.newFixedThreadPool(4);
    final ObjectProperty<Cursor> CURSOR_DEFAULT = new SimpleObjectProperty<>(Cursor.DEFAULT);
    final ObjectProperty<Cursor> CURSOR_WAIT = new SimpleObjectProperty<>(Cursor.WAIT);

    @Override public void start(final Stage primaryStage) {
        primaryStage.setTitle("Combo Sample");

        ComboBox<String> from = new ComboBox<>();
        from.getItems().addAll("DEV", "TEST", "PROD");
        from.getSelectionModel().selectedItemProperty().addListener((observable, oldValue, newValue) -> {
            Task<Void> task = new Task<Void>() {
                @Override protected Void call() throws Exception {
                    System.out.println("selectFrom - Start");
                    Thread.sleep(20000);
                    System.out.println("selectFrom - End");
                    return null;
                }
            };
            primaryStage.getScene().cursorProperty().bind(Bindings.when(task.runningProperty())
                    .then(CURSOR_WAIT).otherwise(CURSOR_DEFAULT));
            pool.submit(task);
        });

        ComboBox<String> to = new ComboBox<>();
        to.getItems().addAll("DEV", "TEST", "PROD");
        to.getSelectionModel().selectedItemProperty().addListener((observable, oldValue, newValue) -> {
            Task<Void> task = new Task<Void>() {
                @Override
                protected Void call() throws Exception {
                    System.out.println("selectTo - Start");
                    Thread.sleep(5000);
                    System.out.println("selectTo - End");
                    return null;
                }
            };
            primaryStage.getScene().cursorProperty().bind(Bindings.when(task.runningProperty())
                    .then(CURSOR_WAIT).otherwise(CURSOR_DEFAULT));
            pool.submit(task);
        });

        HBox layout = new HBox(10);
        layout.getChildren().addAll(from, to);
        primaryStage.setScene(new Scene(layout));
        primaryStage.setWidth(400);
        primaryStage.setHeight(200);
        primaryStage.show();
    }
}