Overwrites other post type rewrite rules

Thanks Jorn, I’ve been exploring this issue myself. I wonder if it has something to do with the order in which the plugins are loaded.

A simple way to reproduce the issue would be to create a super simple plugin with a generic custom post type, activate it, and see if the rewrite rules work. I’ve done just that. Here is the plugin file:

<?php
/*
Plugin Name: Custom Post Type Test
Author: Scott Meves
Version: 1.0
*/

//avoid direct calls to this file, because now WP core and framework has been used
if ( !function_exists('add_action') ) {
header('Status: 403 Forbidden');
header('HTTP/1.1 403 Forbidden');
exit();
}

if ( !class_exists( 'PostTypeTest' ) ) {
  class PostTypeTest {

    function PostTypeTest() {
      register_post_type( 'custom_post_type',
        array(
          'labels' => array(
            'name' => __( 'Custom Name' ),
            'singular_name' => __( 'Singular Name' )
          ),
          'public' => true,
          'rewrite' => array('slug' => 'custom-url-here', 'with_front' => false),
          'hierarchical' => false,
          'capability_type' => 'post',
          'has_archive' => false,
          'publicly_queryable' => true,
          'supports' => array('title', 'editor', 'thumbnail', 'page-attributes')
        )
      );
    }
  } // end class
  // Initiate the plugin
  add_action("init", "PostTypeTestInit");
  function PostTypeTestInit() {
    global $the_customPostType;
    $the_customPostType = new PostTypeTest();
  }
}

When I add this simple plugin, and deactivate the “Custom Post Type Maker” plugin, and then re-save the permalink settings / flush the rewrite rules… sure enough my custom rewrite rule works just fine (“/custom-url-here/…”).

But if I activate the “Custom Post Type Maker” plugin again, the other custom post type rules disappear.