Problem setting up permissions for Tenant in vRA 6.2.2

Hello,

I'm having a hard time setting permissions for the default tenant in vRA 6.2.2 portal, while trying to add new users in the Administration-->Catalog management-->access rights-->users&groups Tab the VRA are unable to locate active directory users altought the SSO is already configured:

I have reconfigured the identity store for the appliance but without any positif result, any idea about what causing the issue ? thanks.