Image Widget Dynamic Shortcode: No output

I’m using Elementor Pro and want to display an image via a custom shortcode as displayed here: https://docs.elementor.com/article/449-dynamic-shortcode

https://i.stack.imgur.com/dTKU8.jpg

But it isn’t working. There is simply nothing displayed. Neither in the editor, nor in the frontend. Also not if I remove the brackets [ ... ] around the shortcode and try brand_banner only.

It does not produce any DOM output in the frontend, just an empty elementor-widget-wrap div:

<div class="elementor-element elementor-element-4f1547ad elementor-column elementor-col-50 elementor-inner-column" data-id="4f1547ad" data-element_type="column">
	<div class="elementor-column-wrap  elementor-element-populated">
		<div class="elementor-widget-wrap">
		</div>
	</div>
</div>

However, if I use a simple text editor widget and put the shortcode in, it works as expected:

https://i.stack.imgur.com/uBf16.jpg

DOM:

<div class="elementor-element elementor-element-37728dd elementor-widget elementor-widget-text-editor" data-id="37728dd" data-element_type="widget" data-widget_type="text-editor.default">
	<div class="elementor-widget-container">
		<div class="elementor-text-editor elementor-clearfix">
			<img src="https://some.domain.com/wp-content/uploads/banner-a.jpg"></div>
		</div>
	</div>
</div>

This is the code for the shortcode:

public function shortcode_brand_banner( $atts )
{
	$brand = $this->getRandomBrandFromPool();
	// Return the rendered image HTML.
	return ( types_render_field( 'image-brand-banner', [ 'post_id' => $brand->post->ID ] ) );
}

I thought maybe it is because it doesn’t expect HTML, but rather an image URL. So I changed the code to this, but it doesn’t work either:

public function shortcode_brand_banner( $atts )
{
	$brand = $this->getRandomBrandFromPool();
	// Only return image URL like "https://some.domain.com/wp-content/uploads/banner-a.jpg"
	$image = get_post_meta( $brand->post->ID, 'wpcf-image-brand-banner' )[ 0 ];
	return ( $image );
}

What is the problem here? Is this a bug in Elementor Pro? What kind of output does the Widget expect?