Post type field is not empty when cloned

Using the following code to create a clonable 'Post' field which is select_advanced:

add_filter('rwmb_meta_boxes', function($meta_boxes) {
	
	$meta_boxes[] = array(
		'id' => 'metabox_id',
		'title' => 'Metabox Title',
		'context' => 'normal',
		'fields' => array(
			array(
				'name' => 'Select a Post',
				'id' => 'select_a_post',
				'type' => 'post',
				'post_type' => 'cpt_name',
				'field_type' => 'select_advanced',
				'multiple' => true,
				'clone' => true,
			),
		),
	);
	
	return $meta_boxes;
	
});

When the "+ Add more" button is clicked, the field is prefilled with the latest cpt of that type - https://imgur.com/a/lzurPEZ

I would like the field to be empty when cloned. How can I do this?

I am using the default TwentySixteen theme and no other plugins are active other than Classic Editor.

Metabox version 5.10.8
WP version 6.7.2