Hierarchal custom post type drop down, need help…

I’m working on this page: https://babyboomergold.savydev.com/browse-offers

It allows users to search a custom post type and it’s related taxonimies (states and cities as well as categories).

However, I can’t make the drop down hierarchal for some reason (it doesn’t accept the hierarchal argument). Here’s my code:

Functions.php
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my-page.php
<?php dropdown_search('states-and-cities', array( 'taxonomy' => 'states-and-cities', 'hierarchical' => true, 'show_option_none' => ' ', 'hide_empty' => 1, 'orderby' => 'name', 'order' => 'asc', 'name' => 'states-and-cities' )); ?>

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