Make GC Sermons 'Series' Taxonomy hierarchical. A possible workaround for https://core.trac.wordpress.org/ticket/14691

gc-sermons-series-taxonomy-to-hierarchical.php

<?php 

function series_taxonomy_override( $args ) {
	$args['arg_overrides']['hierarchical'] = true;

	return $args;
}
add_filter( 'gcs_taxonomies_series', array( $this, 'series_taxonomy_override' ) );