My three sagos are not flushing new fronds, either. The only thing I can think to do at this point is to wait and see. I always leave the cones and flowers on in past years and had the usual new set of fronds. This year is a bit different for some reason. Maybe for this season, the plant's energy needs to be regulated to propagating first and then the leaves sprout? Since you have a good set of sagos, I would not worry. We always have pups set in pots for backups or for sale and to give away. I honestly think our three plants are enough.