Hmmm. Possibly because they are being purchased through the USN rather than a direct purchase through Boeing? Therefore being wrapped up in successive USN orders - like the first Australian airframe is included in the 13 airframes in USN tranche 2?
If you look at
the Boeing press release on the tranche they mention the Australian first airframe. But if you scroll down on the page that links to the press releases -
only the USA and India are mentioned as customers.
Following the same logic, they won't put up anything directly relating to the RAF order, but will state when their airframes are included in subsequent USN tranches.
Just an opinion.