GUI behaves differently in IDE vs command line

Question

I'm writing a GUI application in Java, and using Eclipse. However, the result of the code behaves differently when I compile and run using command line vs in the IDE itself. Here's the code:

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;
import javafx.scene.text.Text;
import javafx.scene.text.Font;
import javafx.scene.text.FontWeight;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.control.PasswordField;

public class MainGUI extends Application
{
    public static void main (String args[])
    {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) throws Exception 
    {
     primaryStage.setTitle("Citation Machine");
     GridPane grid1 = new GridPane();
     grid1.setAlignment(Pos.CENTER);
     grid1.setHgap(10);
     grid1.setVgap(10);
     grid1.setPadding(new Insets(20, 0, 0, 0));
     Label l = new Label("Welcome. Please enter your URL.");
     grid1.add(l, 0, 0);
     TextField urlField = new TextField();
     grid1.add(urlField, 0, 1);
     Button submit = new Button("OK");
     submit.setOnAction(e -> System.out.println(urlField.getText()));
     grid1.add(submit, 1, 1);

     GridPane grid = new GridPane();
     grid.setAlignment(Pos.TOP_CENTER);
     grid.setHgap(10);
     grid.setVgap(10);
     grid.setPadding(new Insets(20, 0, 0, 0));
     Text scenetitle = new Text("Welcome");
     scenetitle.setFont(Font.font("Tahoma", FontWeight.NORMAL, 20));
     grid.add(scenetitle, 0, 0, 2, 1);

     Label titleLabel = new Label("Article Title:");
     grid.add(titleLabel, 0, 1);

     TextField title = new TextField();
     grid.add(title, 1, 1);

     Label authorLabel = new Label("Author:");
     grid.add(authorLabel, 0, 2);

     TextField author = new TextField();
     grid.add(author, 1, 2);

     Label webTitleLabel = new Label("Website Title:");
     grid.add(webTitleLabel, 0, 3 );

     TextField webTitle = new TextField();
     grid.add(webTitle, 1, 3);

     Label publisherLabel = new Label("Website Publisher:");
     grid.add(publisherLabel, 0, 4);

     TextField publisher = new TextField();
     grid.add(publisher, 1, 4);

     Label urlLabel = new Label("URL:");
     grid.add(urlLabel, 0, 5);

     TextField url = new TextField();
     grid.add(url, 1, 5);

     Label monthLabel = new Label("Month of Publication:");
     grid.add(monthLabel, 0, 6);

     TextField month = new TextField();
     grid.add(month, 1, 6);

     Label dayLabel = new Label("Day of Publication");
     grid.add(dayLabel, 0, 7);

     TextField day = new TextField();
     grid.add(day, 1, 7);

     Label yearLabel = new Label("Year of Publication:");
     grid.add(yearLabel, 0, 8);

     TextField year = new TextField();
     grid.add(year, 1, 8);

   //  grid.setGridLinesVisible(true);
     Scene urlChecker = new Scene(grid1, 300, 150);
     Scene information = new Scene(grid, 400, 500);
     primaryStage.setScene(urlChecker);
     primaryStage.show();
    }

}

When I compile and run through CL, it works as expected, printing "pressed" to the CL when the button is clicked. When I run it through the IDE, nothing happens. Why does this occur?