I’m using this code which works really fine to list quite everything I need as Featured image and title, from my custom posts "portfolio".

<?php
    $args  = array(
    'posts_per_page'  => 5000,
    'offset'          => 0, 
    'orderby'         => 'title',
    'order'           => 'ASC',
    'post_type'       => 'portfolio',
    'post_status'     => 'publish',
    'suppress_filters' => true ); 
    $posts = get_posts($args);
    foreach ($posts as $post) :
    ?>
    
    <div class="grid-item">
        <a href="<?php the_permalink();?>">
            <div class="grid-image <?php echo get_the_category()?>">
                <h2 class="grid-title"><?php echo the_title();?></h2>
                <?php echo the_post_thumbnail(array(360,360));?>
            </div>
        </a>
    </div> 

But now, I’d like to list only posts from a choosen category. I tried to add these following terms in args but nothing seems to work.

'category'      => 'category-slug',
'category'      => category-id, 

Any advice on this ? Many Thanks