Can't list user in a role?

Hello,

Here is what I have :
realm : customers
client-id : my client
role of this client : test

I added this role to a user, but when I check the UI I can’t see any user
if I try getting the user in role via API, same result : https://sso-clt.nordnet.fr:443/auth/admin/realms/customers/clients/bfa11ddb-277a-409f-a64e-babec28d2f51/roles/test/users

any idea what could be wrong ?