Highlight current category in wp_list_categories

I am using wp_list_categories to display all terms of my custom taxonomy 'categories'.

The function is outputting all my terms successfully but the current category is not being highlighted, even though 'current_category' is set to 1 in my arguments.

The function is being outputted on taxonomy-categories.php, following the naming convention of my taxonomy categories.

It is not inside a loop, could that be why?

UPDATE, here is my function:

$args = array(
    'orderby'               => 'term_group',
    'title_li'              =>  NULL,
    'order'                 => 'ASC',
    'hide_empty'            => 1,
    'use_desc_for_title'    => 0,
    'feed'                  => '',
    'hierarchical'          => 1,
    'echo'                  => 1,
    'current_category'      => 1,
    'taxonomy'              => 'categories'
);
echo wp_list_categories($args);

Note: this works on my single-{post-type}.php template, but does not function on my taxonomy-{taxonomy}.php template.