Anyone know what are BAs business rules around releasing CW seats for redemption? Looking for a ticket to HK and there are tons of seats on both flights on the day I am after but no award availability
The only rule is that when bookings open for that flight (about 355 days before the flight), there are guaranteed to be two CW award seats available at that time. And that means "at that time"; sometimes these can be booked within a matter of seconds.
Other than that, it is purely at BA's commercial discretion. Remember that the airline's aim is not to fill the aircraft; any fool can do that. It is not even to make the maximum revenue possible on that specific flight. The aim is to make the operation make the maximum profit on a sustainable long-term basis, and that can mean deliberately flying with empty seats even if people would like to get those seats at a cut-price rate by upgrading using Avios. This is the reasoning underlying BA's frequent decision not to make award seats available.
You don't say when your flight is, but there are three things to bear in mind which are increasingly true the further away the flight is. First, you can have no idea how many reservations BA has taken for the CW cabin on your flight. Second, you can have no idea how the current booking level matches the predicted booking profile at this point in the year-long selling cycle. Third, you can have no idea whether BA expects to be able to sell every single seat in the cabin by the time of departure for a better fare than is represented by an upgrade using Avios. All of those things affect whether BA will release any more award seats.