I would bet a year's pay that they could not place an inconspicuous hold on the electronic tracking intentionally even if they WANTED to.
It's federal, and already in the system, so I can almost positively guarantee the reason it's not showing up is either a) data malfunction or b) mishap or loss of package or container with the package.

I would bet almost anything that they could not intentionally, manually manipulate an already-working automated system... so I'd say it's definetely because of the defacto reason behind the "you may not be able to track" disclaimer. They're just not sharp enough to pluck out one transaction without leaving a log that would be obvious for you to see. My opinion, based on knowledge of tech and federal bumbling.....

Peace
J