MB Relationships - Using each_connected multiple times

I'm having trouble setting up the each_connected multiple times example. My project has three post types - products, groups, manufacturers - and I've defined products_to_groups and products_to_manufacturers relations.

The single pages work as expected and correctly display the linked items.

The archive page is where it has problems. I set up the loop:

    $my_query = new WP_Query( array( 
        'post_type' => 'products' 
    ) );

And get the connected items:

    MB_Relationships_API::each_connected( array(
        'id'   => 'products_to_groups',
        'from' => $my_query->posts, 
        'property' => 'connected_groups',
    ) );

    MB_Relationships_API::each_connected( array(
        'id'   => 'products_to_manufacturers',
        'from' => $my_query->posts, 
        'property' => 'connected_manufacturers',
    ) );

And try to perform the loop, displaying the connected items:

    
    while ( $my_query->have_posts() ) : $my_query->the_post();

        foreach ( $post->connected_groups as $post ) : setup_postdata( $post );
            the_title(); 
        endforeach;
        wp_reset_postdata(); 

        foreach ( $post->connected_manufacturers as $post ) : setup_postdata( $post );
            the_title();  
        endforeach;
        wp_reset_postdata();  

    endwhile; 

The first foreach works and shows the connected groups. The second fails with an "invalid argument" warning. If I switch the inner foreach loops, the first succeeds & the second fails again.

What am I doing wrong? Thanks!