Display fields in frontend

Hi, I am trying to display a text_datetime_timestamp field on the frontend in a post with a different format, since it is a UNIX date.

The metabox with the respective field is the following:

add_action( 'cmb2_init', 'ccb_register_metabox' );
/**
 * Hook in and add a demo metabox. Can only happen on the 'cmb2_init' hook.
 */
function ccb_register_metabox() {

	// Start with an underscore to hide fields from custom fields list.
	$prefix = 'ccb_';

	/**
	 * Sample metabox to demonstrate the different conditions you can set.
	 */
	$cmb = new_cmb2_box( array(
		'id'            => $prefix . 'metabox',
		'title'         => 'Valoración de la composición corporal',
		'object_types'  => array( 'valoraciones' ), // Post type.
    	'show_on_cb' => 'be_taxonomy_show_on_filter', // function should return a bool value
    	'show_on_terms' => array(
	    	   'tipo-valoraciones' => array( 'tvf-cc' ),
	),
	) );

	/**
	 * Group fields works the same, except ids only need
	 * to be unique to the group. Prefix is not needed.
	 *
	 * The parent field's id needs to be passed as the first argument.
	 */

    $cmb->add_field( array(
		'name' => esc_html__( 'Fecha y hora', 'cmb2' ),
		'id'   => 'fecha_hora',
		'type' => 'text_datetime_timestamp',
		'default_cb' => 'set_to_today',
		'column' => array(
            'position' => 3,
            'name'     => 'Fecha de valoración',
        ),

	) );

I added the following function and shortcode:

//Mostrar fecha y hora con formato en el frontend
function mostrar_fecha_hora( $field ) {
$text = get_post_meta( $field->object_id, 'fecha_hora', true );
echo date('d/m/Y H:i A', $text ); // resultado 07/03/2016 08:40:00 AM
}

add_shortcode( 'fecha_hora_formateada', 'mostrar_fecha_hora' );

And the short code in the post is:
[fecha_hora_formateada]

But I can’t get it to display on the frontend.

What am I doing wrong?

Thank you very much in advance.