I've been making theme's using custom post types for a while, but for some reason the current theme isn't loading the single-cpt.php for a single cpt post.
How does WordPress recognize that the current object is a single post?
I made a custom rewrite rule, bases on a meta_key and meta_value. Is that the problem and should it contain an ID/slug/etc?
Apperently, WordPress isn't able to find out that it's a single post. How can I still use this query vars, but use the single-book.php template?