Yesterday a new ConfigMgr 2012 R2 Policy Hotfix is released. This because Per-computer task sequence variables that are defined for imported computers are filtered out of client policies. This prevents the variables from being read during task sequence execution. This problem does not affect per-computer variables that are defined for existing clients.
This update applies only to Primary sites.
Important Per-computer task sequence variables have to be recreated if they were created after System Center 2012 R2 Configuration Manager was installed but before this update is applied.
You can download the Hotfix here: Microsoft Support