Custom Taxonomy correctly works on slugs with multiple words, not single term slugs

Here’s the code for my custom taxonomy.

Whenever there’s a taxonomy that has multiple terms such as ‘Action Adventure’, it would list and display any items in a proper manner. But if the taxonomy is a single term such as ‘Drama’, the page would only display the index.php of the WordPress theme. Basically it has something to do with the presence of a ‘-‘ character present in the slug that seems to make the difference.

Oh, there is no Custom Post Type related to this custom taxonomy.

What am I doing wrong?