I had the same problem as here: pages rendered blank or only semi-rendered. After moving the line require_once(ABSPATH . 'wp-settings.php');
to the end of the wp-config.php file, where it now resides right after define ('WP_ALLOW_MULTISITE', true);
and the rest of the multisite-code, the problem was fixed.
IMO, Andrea’s (otherwise very good) document doesn’t mention this. Maybe it should?