Sounds like you need a queen, I wouldn't bet on the one that PROBABLY HATCHED - if you still aren't seeing eggs or larva - I'd be calling someone or somewhere to get a queen in that hive.
Having NEVER seen brood but seeing a queen cell deconstructed, I'd serious wonder what is happening - but it doesn't seem that it would be too tough to find a queen if she WAS in there. Literally take that hive apart one frame at a time, search it all closely looking for her and brood - drone eggs ould be a bummer, but I don't know if you are talking laying worker, sounds like you might be stuck with a lame queen or no queen - either way, you need a healthy queen to give that hive a booster shot.
I agree, active hives almost always mean that a PHEROMONE SCENT is present i the hive - even a weak one is better than none at all. Having lots of honey is great, but your bees are getting old and their production will start to slow as the average age of your workers enter their golden years.
Is there anything else you can tell us?