Suggestion for stages:
A cacher visits a cache where a trackable is listed, but it's not in the cache. They log this on the trackable's page using a new logtype: Not in Cache. This notification goes to the TO and CO.
Additionally, this logging action automatically "greys out" that trackable from that cache inventory. (Not removes it completely, just greys out the text a bit - It could even be referred to as "ghosting the trackable". That would be enough to alert everyone that the tracka