Wordpress is unable to query post types with hierarchical set to 'true' when there is 'order' registred post type

[MateuszP1]

Problem occurs when you register post type named 'order'

<?php
$labels = array(
"name" => "Orders",
"singular_name" => "Order",
);

$args = array(
"labels" => $labels,
"description" => "",
"public" => true,

);
register_post_type("order", $args);

it breaks queries of posts types with hierarchical set to true, even 'page' post type.
See:
wp-admin/edit.php?post_type=page
after registering this post type.

[jadpm]

​https://codex.wordpress.org/Reserved_Terms

"order" is a reserved word so post types shoud not rgister with that slug.

[SergeyBiryukov]

Hi @MateuszP1, welcome to Trac! Thanks for the ticket.

As noted above, order is one of the reserved terms and should not be used as a post type key. Try using my-order or something similar instead.

[swissspidy]

Here's the list of reserved terms btw: ​https://codex.wordpress.org/Reserved_Terms

[MateuszP1]

ahh, ok thanks!