Change the “author_link”

Hello everybody,

I try to change the author_link only for a special Custom Post Type.

But the is_singular () does not work. I created the CPT with CPT UI Plugin.

Here is my code:

function my_author_link( $link ) {	
	if ( is_singular( 'localhero_profile' ) ) {
		global $post;
			$profile_ID = get_user_meta($post->ID, '_cptID', true);
			$link = get_permalink( $profile_ID );
		return $link;
	} else {	
		return 'HELLO';	
	}
}
add_filter( 'author_link', 'my_author_link', 10, 1 );

Any suggestion why it does not check if its the CPT “localhero_profile”?

Cheers,
Denis