No top menu in admin - Perch 2.8.26

I have just updated to Perch 2.8.26 and now my header navigation has vanished in the admin i.e.: Pages, Assets, Apps, Users. The update went smoothly, no error messages, and update was successful.

SUMMARY INFORMATION

Perch: 2.8.26, PHP: 5.5.32, MySQL: 5.5.47, with PDO
Server OS: Linux, cgi-fcgi
Installed apps: content (2.8.26), assets (2.8.26), categories (2.8.26), perch_blog (5.0), perch_forms (1.8.2), perch_gallery (2.8.5), perch_backup (1.2)
App runtimes: <?php $apps_list = array( 'content', 'categories', 'perch_blog', 'perch_gallery', 'perch_forms', ); ?>
PERCH_LOGINPATH: /perch
PERCH_PATH: /www/sites/b47/a33/www.mywebsite.com/web/perch
PERCH_CORE: /www/sites/b47/a33/www.mywebsite.com/web/perch/core
PERCH_RESFILEPATH: /www/sites/b47/a33/www.mywebsite.com/web/perch/resources
Image manipulation: GD
PHP limits: Max upload 1024M, Max POST 1024M, Memory: 256M, Total max file upload: 256M
F1: 2edba60ed1f613d6dd804feb202456a2
Resource folder writeable: Yes
SCRIPT_NAME: /perch/core/settings/diagnostics/index.php
REQUEST_URI: /perch/core/settings/diagnostics/
DOCUMENT_ROOT: /www/sites/b47/a33/www.mywebsite.com/web
HTTP_HOST: www.mywebsite.com