Not filtering DEFAULT template pages => SOLUTION here

To filter “non-templated” pages — the pages with the default WordPress page.php behavior — you need to modify the metaquery to:

array(
	'meta_query' => array(
		array(
			'key'     => '_wp_page_template',
			//'value'   => $template_files,
			'compare' => 'NOT EXISTS',
		)
	),
)

I did that adding one more instance in the IF/ELSE statement on line #57. I created a new ELSEIF with “default”, just like the same as “all_missing”, and used the meta quert above. Please note I did comment out the VALUE and changed to “NOT EXISTS” only.

Regards!
G.