WP_MEMORY_LIMIT didn’t work in wp-config, only within default-constants.php

Your code appears to be using he incorrect quote characters. You have ’ instead of '. This can happen if you copy it from a site where the quotes have been converted to ‘fancy quotes’ by the publishing platform but the author didn’t catch it.

So replace

define(‘WP_MEMORY_LIMIT’, ’128M’);

With

define('WP_MEMORY_LIMIT', '128M');