Not sure if anyone else is having this problem, but my HDR is refusing to pick up the newest HD channels such as BBC4 HD and BBC News HD on an auto tune. It picks up BBC3 HD for instance just fine, along with all other channels.
The two HD-FOX T2 boxes in my house are picking these newest channels up fine on an auto tune, so the definitely are there to be watched.
Or the aerial feed to that that particular device. Have you tried it swapping the feed from one of the boxes that does find these channels? Note also that these channels are on a MUX with a much lower power transmission than the other MUXes so it could be tuner sensitivy is marginal where you are.