If your figures connected to taxonomies, then you can filter by tax_query
Your query has to look like this:
// filter on figures from serie's taxonomy
$args = array(
'post_type' => 'figure',
'posts_per_page' => -1,
'meta_key' => 'release_date_fr',
'orderby' => 'meta_value',
'order' => 'DESC',
'tax_query' => array(
array(
'taxonomy' => 'serie', // taxonomy name
'field' => 'slug', // term_id, slug or name
'terms' => array( 'the-legend-of-zelda', 'hyrule-warriors' ), // single value or array of term id(s), term slug(s) or term name(s)
)
)
);
// query the figures
$the_query = new WP_Query($args);
BTW: If there is a error 500, then there is a new entry in you error logs, with more details about the error. Always start at this point to look for a solution.
