Filter Custom Post Type by Category with Ajax

Nevermind, I’ve managed to solve it. For anyone interested, the problem was ‘category__in’ isn’t support by custom post types so instead needed to edit the $args array to include ‘tax_query’.

$args = array(
        'post_type' => 'libraries',
        'tax_query' => array(
            array(
                'taxonomy' => 'library_types',
                'terms'    => $category
            ),
        ),
    );