How to add a custom taxonomy to a custom post type’s document tab

I created a custom taxonomy and wanted to add it to the side-menu of my portfolio custom post type (in the admin area). My custom taxonomy is not loading, but the default one (‘category’) does. What did I miss? add_action( ‘init’, ‘add_taxonomies’ ); function add_taxonomies() { register_taxonomy( ‘related_service’, ‘portfolio’, array( ‘label’ => ‘Related Services’, ‘public’…

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