iPlayer not playing in HD


Is anyone having problems getting HD programmes to play in iPlayer? Most HD programmes I try to watch display a blank screen for a few seconds then return to the menu. The same programmes play fine in SD. For example, I can't watch any episode of Africa in HD, but Charlie Brooker's Weekly Wipe and Wonders of Life will play in HD for me.

I've noticed this since upgrading from official firmware 1.02.29 to custom firmware 1.02.32, but to be fair, I only watched a couple of HD shows before the upgrade, so the problem may have already existed. However, one of those programmes was Genius of Invention, which won't play now.