Some clients have been not been logged out for user

We are using Keycloak 3.4.0 final and recently we are seeing following error for couple of users.
[org.keycloak.services.managers.AuthenticationManager]
some clients have been not been logged out for user <user.id> in realm:
We tried to restart key cloak servers
forced out the sessions and we don’t see any session for that user
restarted OpenLDAP to kill any session
but eventually no luck. Any guidance is highly appreciated on this topic.