Components Within Notification does not show

Flow
1

The notification opens in the middle of the screen, but it doesn’t matter what components I add to the notification, they just wont display. All I get is a small empty white square box. I’ve tried this with Vaadin 15 and 16 and see the same behavior.

myComponent
        .getUI()
        .ifPresent(
            ui ->
                ui.access(
                    () -> {
						ProgressBar bar = new ProgressBar();
						bar.setIndeterminate(true);
						Notification notification = new Notification(bar);
						notification.setPosition(Position.MIDDLE);
						notification.open();
					}));
2

Update, if I add a Button after the progress bar, then the progress bar appears. Am I missing something here, or is this a bug?

myComponent
        .getUI()
        .ifPresent(
            ui ->
                ui.access(
                    () -> {
						ProgressBar bar = new ProgressBar();
						bar.setIndeterminate(true);
						Notification notification = new Notification(bar);
						notification.setPosition(Position.MIDDLE);
						notification.add(new Button("HI"));
						notification.open();
					}));
3

The issue here seems to be that the progress bar doesn’t have an inherent size, which messes up the popup sizing. You can fix it by giving it a size like bar.setWidth("300px");