get_terms() not working in the Admin

I am trying to get Advanced Custom Fields to work with custom taxonomies so I can add content to specific taxonomies in WP.

I came across this documentation about adding custom location rules and added a new rule allowing the field group to be added to a category with get_categories() – and it worked perfectly.

But as soon as I tried to use get_terms() with a custom taxonomy instead it stopped listing anything. My code looks like this:

//add filter that lets you put a custom field group on a specific category in ACF
add_filter('acf/location/rule_types', 'acf_location_rules_types');
function acf_location_rules_types( $choices )
{
    $choices['Forms']['custom_taxonomy'] = 'Custom Taxonomy';

    return $choices;
}

add_filter('acf/location/rule_values/category', 'acf_location_rules_values_category');
function acf_location_rules_values_category( $choices )
{

    $terms = get_terms('ranges',
      array(
          'hide_empty'=> FALSE)
      );

    if( $terms )
    {
        foreach( $terms as $term )
        {
            $choices[ $term->term_id ] = $term->name;
        }
    }
    return $choices;
}

add_filter('acf/location/rule_match/category', 'acf_location_rules_match_category', 10, 3);
function acf_location_rules_match_category( $match, $rule, $options )
{
    $current_cat = $_GET['tag_ID'];
    $selected_cat = (int) $rule['value'];

    if(isset($current_cat)){
      if($rule['operator'] == "==")
        {
          $match = ( $current_cat == $selected_cat );
        }
        elseif($rule['operator'] == "!=")
        {
          $match = ( $current_cat != $selected_cat );
        }

      return $match;
    }
}

My issue is with the foreach loop in the rule_values section – it should be listing the terms as it listed the categories.

Does anyone have any idea why it might not be working?

I have asked in the ACF forum but no luck.