Dropdown title

I’m trying to use the widget_categories_dropdown_args filter to change the title of the dropdown category widget. I have this code in my functions.php:

function ChangeSelectTitle($cat_args){
$cat_args['show_option_none'] = __('Select Whatever');
return $cat_args;
}
add_filter('widget_categories_dropdown_args', 'ChangeSelectTitle');

I set it up previously and I’m pretty sure it was working. Any ideas?
Thanks