Power words not detected

Hi.

I’m using the power words “How to” in a post title. Rank Math give the error “Your title doesn’t contain a power word. Add at least one.”

I’ve disable all plugins, including my page builder, and the error is still displayed.

I’ve added the following code snippet to my child theme’s functions file.
/**
* Filter to add custom Power Words
*/
add_filter( ‘rank_math/metabox/power_words’, function( $words ){
$new_words = [
‘How to’
];
return array_merge( $words, $new_words );
});

YOu can view the page at https://atomiceducation.tech/blog/how-to-write-a-story-based-email/

Help?