Group added to a user disappear after a reconnection

Hello, we have an odd bug on our Server. Do you have any idea?

Steps to reproduce

1.Add a new group to an user
2.User is deconnecting
3.the new group is not affected on the user

Expected behaviour

The group affected on the user's interface stay on the account

Actual behaviour

The group disappear

Server configuration

Operating system: Redhat

Web server: Apache

Database: MariaDB

PHP version:7

ownCloud version: 10.0.2

Updated from an older ownCloud or fresh install: older owncloud

Where did you install ownCloud from:

Signing status (ownCloud 9.0 and above):

Login as admin user into your ownCloud and access 
paste the results into and puth the link here.

The content of config/config.php:

Log in to the web-UI with an administrator account and click on
'admin' -> 'Generate Config Report' -> 'Download ownCloud config report'
This report includes the config.php settings, the list of activated apps
and other details in a well sanitized form.


If you have access to your command line run e.g.:
sudo -u www-data php occ config:list system
from within your ownCloud installation folder

*ATTENTION:* Do not post your config.php file in public as is. Please use one of the above
methods whenever possible. Both, the generated reports from the web-ui and from occ config:list
consistently remove sensitive data. You still may want to review the report before sending.
If done manually then it is critical for your own privacy to dilligently
remove *all* host names, passwords, usernames, salts and other credentials before posting.
You should assume that attackers find such information and will use them against your systems.

List of activated apps:

If you have access to your command line run e.g.:
sudo -u www-data php occ app:list
from within your ownCloud installation folder.

*Are you using external storage, if yes which one: NO

Are you using encryption: yes/no NO

**Are you using an external user-backend, if yes which one: NO


Web server error log

No error

ownCloud log (data/owncloud.log)

No error

It's due to an old parameter. Solved