Save_post acf data not updating category of post type

You can not use is_single() conditional tag here.

You can check the type of post in the function this way:

add_action( 'save_post', 'set_genre_on_save', 20, 3 );
function set_genre_on_save( $post_id, $post, $update ) {
    if ($post->post_type != 'hvm')
        return;

    // ...
}  

You can also attach the function to the action hook save_post_{post_type}, which is triggered only for the {post_type} type. Then there is no need to check the type of post inside the function.

add_action( 'save_post_hvm', 'set_genre_on_save', 20, 3 );