As noted in the logs for the cache in which it was last seen, your trackable went missing, along with the cache container. I am moving your trackable to an "unknown location." (This option is also available to the cache owner and to the owner of the travel bug or geocoin.) If it ever turns up again, the finder can grab it back without affecting the mileage. I am sorry that your trackable has stopped traveling.
Keystone
Geocaching.com Volunteer Cache Reviewer