Meta_Query refuses to return results

You forgot the meta_query key in your $args.

$meta_query = array(
    'relation' => 'OR',
    array(
        'key'     => 'tic_assignment',
        'value'   => $current_user -> ID,
        'compare' => '=',
    ),
    array(
        'key'     => 'tic_department',
        'value'   => $_depts,
        'compare' => 'LIKE',
    ),
);
$_args = array ( 'post_type' => 'tickets',
    'meta_query' => $meta_query,
    'posts_per_page' => 10, 
    'orderby' => 'date', 
    'order' => 'DESC', );
$the_query = new WP_Query( $_args );