Taxonomy related query not working

The final code I used was:

<?php
$slides_category = get_field('slider_category');
$args = array(
    'post_type' => 'slides_post_type',
    'tax_query' => array(
        array(
            'taxonomy' => 'category',
            'field'    => 'id',
            'terms'    => array( $slides_category ),
        ),
    ),
);
$slides_loop = new WP_Query( $args );
if( $slides_loop->have_posts() ): while( $slides_loop->have_posts() ): $slides_loop->the_post(); ?>
     // Post content goes here
<?php endwhile; ?>