The sync User Script (auth/db/cli/sync_users.php) create User with a wrong mnesthostid, every time with the ID = 1.
It must manual changed on database, to the correct mnethostid.
On mdl_config is the Value (4) for mnet_localhost_id and on mdl_mnet_host the primary Key ID (4).
We host many moodle instances and all have a different mnesthostid. This failure is new with Moodle 2.9.5, not in the earlier version 2.9.3