I experience an issue with ldap group sync in 1.9.2. Foreman raises an 500 exception with "LdapFluff::ActiveDirectory::MemberService::UIDNotFoundException".
This happens when adding, refreshing or deleting the group.

I tested with a single group. That group contains only valid users. They are not all known to foreman, though. (as they have not logged in before)
I checked the base dns. All users in the group can possibly be found.
I tested with active directory.

Trace:
http://pastie.org/private/hwh9s12plur2bz9fsqytg