Update Issue "using attributes in menus"

I used to follow this instruction and it worked perfectly:
https://docs.woothemes.com/document/using-custom-attributes-in-menus/

However, after the update the solution doesn’t work anymore.
Here is the sample code:

add_filter(‘woocommerce_attribute_show_in_nav_menus’, ‘wc_reg_for_menus’, 1, 2);
function wc_reg_for_menus( $register, $name = ” ) {
if ( $name == ‘pa_size’ ) $register = true;
return $register;
}

I tried this on a new and clean install with only Woocommerce and the latest WordPress

Please help me.

https://www.ads-software.com/plugins/woocommerce/