Using ACF plugin to display posts in relationship with portfolio

Hi,
I need to display a list of related post types to the current portfolio item.
I use ACF to build relation between portfolio item and post types.
I have added related post-types to current portfolio item.
I have edited /config-templatebuilder/avia-shortcodes/portfolio.php file adding:

Basic loop (with setup_postdata):

$postx = get_field('your_business_product_items');
if( $postx ):
  $output .="	  <ul>";
     foreach( $postx as $post): // variable must be called $post (IMPORTANT) 
         setup_postdata($post); 
        $output .="	<li>";
			$output .="	<a href=";
			the_permalink(); 
			$output .=">";
			the_title(); 
			$output .="	</a>";
            $output .="	<span>Custom field from $post:";
			the_field('author');
			$output .="	</span>";
        $output .="	</li>";
     endforeach; 
    $output .="	</ul>";
     wp_reset_postdata(); // IMPORTANT - reset the $post object so the rest of the page works correctly 
 endif; 

or basic loop (without setup_postdata)

 
$postz = get_field('your_business_product_items');
 if( $postz ): 
 	$output .="<ul>";
	 foreach( $postz as $p ): 
$output .="	    <li>";
	    	$output .="<a href='";
			echo get_permalink( $p->ID ); 
			
			$output .="'>";
			
			echo get_the_title( $p->ID );
			$output .="</a>";
	    	
			$output .="<span>Custom field from"; 
			
			the_field('author', $p->ID);
			
			$output .="</span> </li>";
	 endforeach; 
	$output .="</ul>";
 endif;

But nothing appears.
Anyone tried to do this?

I display portfolio as a preview on one-page style Enfold.

Thanks.