Users in an Active Directory user store can be successfully authenticated and granted access to protected resources when their password has expired in Active Directory under specific conditions.
Policy Server 12.8.8 and 12.8.8.1;
USER DIRECTORY on Microsoft Active Directory.
Upgrade the Policy Server to 12.9 to solve this issue from fix DE593751 (1).
As a workaround, define the user directory at the Active Directory LDAP Root level.