Acf Pro repeater field returns null [closed]

I’ve just solved this issue thanks to the Avanced WordPress group in Facebook (https://www.facebook.com/groups/advancedwp/). It was actually a mistake I had made: I had a query before the custom fields and it had to be reset. This is the working snippet:

<?php
    // WP_Query arguments
    $args = array (
        'post_type'              => 'post',
        'posts_per_page'         => '4',
    );

    // The Query
    $query = new WP_Query( $args );

    // The Loop
    if ( $query->have_posts() ) {
        while ( $query->have_posts() ) {
            $query->the_post();
            the_title();
        }
    } else {
        echo 'No posts found';
    }

    // Restore original Post Data: this line was missing in my original code; adding it solved the issue.
    wp_reset_postdata();
?>

<?php if( have_rows('logo_grid_logos') ): ?>
    <?php while( have_rows('logo_grid_logos') ): the_row(); ?>
        <img src="https://wordpress.stackexchange.com/questions/188440/<?php echo get_sub_field("logo_grid_img'); ?>">
    <?php endwhile; ?>
<?php endif; ?>

My original query is a little more complex but this is a working example.
Thanks!