I am on max and had to do a factory reset keep recordings in maintenance mode to get them to work.
Im on Entertanment Max and I get all HD channels so you should get all channels.
@Wonder if BT will try for the other ITV and Channel 4 channels in HD.'
They have been availiable in HD on my box for a few years ! Could it be your transmission area that does not have them ?
How do you get those channels @ZooBurner when no-one else can? They don't even appear on Freesat. I thought ITV2-4 and E4/More4 in HD were exclusively behind the paywall and only on Sky? I could be wrong.