Probably no rooms are available on points because of the block. You’re probably out of luck. But the room rates for the block should at least be semi competitive so points may not have been the best use anyway. If you still want to use points you can check when the block booking expires. They may release unsold rooms for points booking at that point. But I would make a block booking if you want to stay in case no rooms become available. It’s not possible to use points for a block booking.