Exclude RP4WP categories

rp4wp-exclude-category.php

function rp4wp_exclude_category( $sql, $post_id, $post_type ) {
	global $wpdb;

	if ( 'post' !== $post_type ) {
		return $sql;
	}

	$sql_replace = sprintf( "
	INNER JOIN " . $wpdb->term_relationships . " ON (R.`post_id` = " . $wpdb->term_relationships . ".object_id)
	INNER JOIN " . $wpdb->term_taxonomy . " ON (" . $wpdb->term_relationships . ".term_taxonomy_id = " . $wpdb->term_taxonomy . ".term_taxonomy_id)
	WHERE 1=1
	AND " . $wpdb->term_taxonomy . ".taxonomy = 'category'
	AND " . $wpdb->term_taxonomy . ".term_id NOT IN ( %s )
	", " 100,200,300 " );

	return str_ireplace( 'WHERE 1=1', $sql_replace, $sql );
}

add_filter( 'rp4wp_get_related_posts_sql', 'rp4wp_exclude_category', 11, 3 );

I just spent about two hours trying to get this to work and unfortunately it appears not to work at all. I changed

	AND " . $wpdb->term_taxonomy . ".term_id NOT IN ( %s )
	", " 100,200,300 " );

to

	AND " . $wpdb->term_taxonomy . ".term_id IN ( %s )
	", " 1 " );

which should have prevented most of my posts from appearing. I then re-ran the wizard to cache and link the posts and it's still including all the posts.

UPDATE: I just added some logging and ran a test. It looks like rp4wp_get_related_posts_sql is never called, not when the posts are cached and linked, not when the page is rendered, never.