Libgdx Scene2D Table background image not showing up

Question

I am using Libgdx's Scene2D API to build by UI and everything has been working as expected until now. I created a Skin and a TextureAtlas and linked them as so:

Skin skin = new Skin();
TextureAtlas uiElements1 = new TextureAtlas("skins/uielements1.txt");
skin.addRegions(uiElements1);
skin.load(Gdx.files.internal("skins/uiskin.json"));

And then I tried to create a Table:

Table table = new Table(skin);
table.setWidth(stage.getWidth());
table.align(Align.center|Align.top);
table.setPosition(0, Gdx.graphics.getHeight());
table.padTop(30);
table.setBackground("grey_button02");

And Finally I added a Label to the Table:

Label gameTitle = new Label("Nameless Project", skin, "title");
table.add(gameTitle).padBottom(10).row();

Once I added the Table to my Stage, only the elements in it would show up and not the background image. I tried using background(String s), setBackground(String s), background(Drawable d), and setBackground(Drawable d). None of those 4 methods seemed to work for me.

I also tried calling pack() and setFillParent(true) but both of those made my table disappear. I have gone through just about every Google result and I can't find anyone else with my issue.

EDIT

Here is my uiskin.json file

{
  com.badlogic.gdx.graphics.g2d.BitmapFont: { default-font: { file: fonts/FutureThin.fnt } },
  com.badlogic.gdx.scenes.scene2d.ui.TextButton$TextButtonStyle: {
   default: { down: blue_button03, up: blue_button04, font: default-font },
  },
  com.badlogic.gdx.scenes.scene2d.ui.Window$WindowStyle: {
    default:  {
      titleFont: default-font
     }
   },
   com.badlogic.gdx.scenes.scene2d.ui.Label$LabelStyle: {
    title: {
        font: default-font
     }
   }
}

And the entire class rendering the stage:

public class MainMenu implements Screen {

    GameClass myGame;

    Stage stage;
    Skin skin;

    Table table;
    TextButton singlePlayer;
    TextButton multiPlayer;
    Label gameTitle;


    public MainMenu(GameClass g) {
        myGame = g;

        // Create Skin, load texture Atlas, load skin
        skin = new Skin();
        TextureAtlas uiElements1 = new TextureAtlas("skins/uielements1.txt");
        skin.addRegions(uiElements1);
        skin.load(Gdx.files.internal("skins/uiskin.json"));

        // Create stage
        stage = new Stage(new ScreenViewport());

        // Create Table
        table = new Table(skin);
        table.setWidth(stage.getWidth());
        table.align(Align.center|Align.top);
        table.setPosition(0, Gdx.graphics.getHeight());
        table.padTop(30);
        table.setBackground("grey_button02");

        // Game Title
        gameTitle = new Label("Nameless Project", skin, "title");
        table.add(gameTitle).padBottom(30).row();

        // Single Player button
        singlePlayer = new TextButton("Single Player", skin, "default");
        singlePlayer.addListener(new ClickListener() {
            @Override
            public void clicked(InputEvent e, float x, float y) {
                myGame.setScreen(new WorldTesting(myGame));
            }
        });
        table.add(singlePlayer).width(300).padBottom(30).row();

        // Multiplayer Button
        multiPlayer = new TextButton("Multiplayer", skin, "default");
        multiPlayer.setWidth(350);
        multiPlayer.addListener(new ClickListener() {
            @Override
            public void clicked(InputEvent e, float x, float y) {
                // Change Scenes
            }
        });
        table.add(multiPlayer).width(300).padBottom(30).row();

        stage.addActor(table);
        Gdx.input.setInputProcessor(stage);
    }

    public void show() {

    }

    public void render(float delta) {
        Gdx.gl.glClearColor(0, 0, 0, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

        stage.act(Gdx.graphics.getDeltaTime());
        stage.draw();
    }

    public void hide(){

    }
    public void resize(int x, int y) {

    }
    public void pause() {

    }
    public void resume() {

    }
    public void dispose() {

    }

}

Answer 1

Finally found the fix. You need to call table.pack() before the background will show up. I was calling table.pack() but positioning the table offscreen after the pack so I assumed the pack() made it disappear.