FortiAuthenticator disconnect Social Logged in users after account expired

FortiAuthenticator disconnect Social Logged in users after account expired. it is all working fine with fortigate 60D and FortiAuthenticator. users are presented with portal and disclaimer page. once user accepted disclaimer policy then they get internet access. its a MAC address portal and their MAC address get into a group in FortiAuthenticator. user account set to expire in 1 hour but even when their account expires they still can browse to internet but it should just disconnect them. any way to fix it please ?