"My sites" link doesn't show up

Hi, I’ve just installed a fresh wordpress with a single user, set the config in wp-config

define( 'WP_ALLOW_MULTISITE', true );

define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', false);
define('DOMAIN_CURRENT_SITE', 'blog.domain.com');
define('PATH_CURRENT_SITE', '/');
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 1);

and .htaccess

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]
</IfModule>

# END WordPress

this is the apache config in the vhost

<Directory /var/www/domain/blog>
                Options -Indexes FollowSymLinks MultiViews
                AllowOverride All
                Order allow,deny
                allow from all
        </Directory>

But when I sign in again I don’t see any “My sites” link in the topbar. I only have one user, so it should be the super admin.

I don’t have any extra themes, plugins or configs, it’s a new wordpress installation with all default settings.

I’ve tried with both wp 4.0 and 3.9.2, same result

When I try to access blog.domain.com/wp-admin/network/sites.php I get “You do not have sufficient permissions to access this page.”

I’ve even tried to put the following in the wp-config.php, with no changes

$super_admins =array( 'adminusername' );

I’m running out of ideas… what should I do to fix it?