Scene2D: How to use Image.setDrawable()

I’m trying to change the texture of an Image actor on my Scene2D stage, however I can’t seem to get it working. It seems like setDrawable() doesn’t really do anything.

For example, this will make the texture of the Image cookie.png:

Image itemImage = new Image(new TextureRegionDrawable(new TextureRegion(new Texture(Gdx.files.internal("cookie.png")))));
itemImage.setPosition(10, 10);
getStage().addActor(itemImage);

However, this will not:

Image itemImage = new Image();
itemImage.setPosition(10, 10);
itemImage.setDrawable(new TextureRegionDrawable(new TextureRegion(new Texture(Gdx.files.internal("cookie.png")))));
getStage().addActor(itemImage);

Am I missing something?