Seems OK to me...with only a few weeks to go to departure, I don't find it odd that the UD has gone for MMB. No window seats is a bit odd, but I guess that's just the way the (enhanced, sleeper service, 'goodnight') cookie crumbles sometimes

Remember only 1/3 of the cabin or so is open for pre-allocation via MMB (I'd link to the exact figures on AskBA if I wasn't on a slow dial-up connection, sorry...) - I doubt you'll have a problem getting either a window to PEK or UD seat from HKG if you OLCI at T-24.
Phil