admin_group doesn't seems to works

Summary

I'm trying to synch admin users from a LDAP server (an Active Directory, in fact) using this method : https://docs.gitlab.com/ee/administration/auth/ldap-ee.html#administrator-sync

group synch seems to work, but I'm not able to grant admin status to users in the admin_group

Steps to reproduce

configure gitlab EE version ( Plan: Starter ) with the following ldap configuration :

  ldap:
    enabled: true
    servers:
      main:
        active_directory: true
        admin_group: G-SF-ADMIN
        attributes:
          email:
          - mail
          - email
          - userPrincipalName
          first_name: givenName
          last_name: sn
          name: cn
          username:
          - uid
          - userid
          - sAMAccountName
        base: dc=YYYY,dc=XXXXX,dc=net
        bind_dn: XXXXXXXXXX
        encryption: ssl
        group_base: OU=GITLAB,OU=DEVOPS,OU=Corporate Resources,DC=YYYY,DC=XXXXX,DC=net
        host: ldap.XXXXX.net
        label: LDAP
        port: 3269
        uid: sAMAccountName
        user_filter: (&(objectClass=user)(memberOf=CN=G-SF-GITLAB,OU=DEVOPS,OU=Corporate Resources,DC=YYYY,DC=XXXXX,DC=net))
        verify_certificates: false
        password: "BBBBBBBB"

The admin_group is located in the group_base

What is the current bug behavior?

Users in group refered by admin_group are not considered as admin in gitlab (no access to Admin Area when authenticated, for exemple)

What is the expected correct behavior?

Access to Admin Area for those users

Relevant logs and/or screenshots

no logs found concerning the ldap activity for this group

Output of checks

license is OK : ldap1 group synch is possible (3 active synchronizations) ldap2 The admin_group (G-SF-ADMIN) is correctly displayed when search for it

Results of GitLab environment info

Helm installation on AWS EKS (kubernetes) 
git@gitlab-task-runner-7d7f94549f-qvqmx:/$ gitlab-rake gitlab:env:info
WARNING: This version of GitLab depends on gitlab-shell 8.4.4, but you're running Unknown. Please update gitlab-shell.


System information
System:
Proxy:          no
Current User:   git
Using RVM:      no
Ruby Version:   2.5.3p105
Gem Version:    2.7.6
Bundler Version:1.16.6
Rake Version:   12.3.2
Redis Version:  unknown
Git Version:    unknown
Sidekiq Version:5.2.5
Go Version:     go1.9.6 linux/amd64


GitLab information
Version:        11.8.2-ee
Revision:       46187896
Directory:      /srv/gitlab
DB Adapter:     postgresql
DB Version:     9.6.8
URL:            https://gitlab.XXXXXXX.net
HTTP Clone URL: https://gitlab.XXXXXXX.net/some-group/some-project.git
SSH Clone URL:  git@gitlab.XXXXXXX.net:some-group/some-project.git
Elasticsearch:  no
Geo:            no
Using LDAP:     yes
Using Omniauth: no


GitLab Shell
Version:        unknown
Repository storage paths:
default:      /var/opt/gitlab/repo
Hooks:          /home/git/gitlab-shell/hooks
Git:            /usr/bin/git

Results of GitLab application Check

Expand for output related to the GitLab application check 
git@gitlab-task-runner-7d7f94549f-qvqmx:/$ gitlab-rake gitlab:ldap:check
WARNING: This version of GitLab depends on gitlab-shell 8.4.4, but you're running Unknown. Please update gitlab-shell.
Checking LDAP ...


LDAP: ... Server: ldapmain
not verifying SSL hostname of LDAPS server 'ldap.XXXXXX.net:3269'
LDAP authentication... Success
LDAP users with access to your GitLab server (only showing the first 100 results)
[... display 50 users ...]
Checking LDAP ... Finished

Possible fixes

(If you can, link to the line of code that might be responsible for the problem)

Edited by Antoine DELOFFRE