A buddy of mine had a swarm capture and wasn't sure he had a queen. Never could find her and wasn't seeing any brood after about three weeks. He grafted a few cells and put them in the swarm hive with a pretty good population. When he checked them a week later, they had drawn the frame slap full of worker cells. You can't even tell it's got the cups or bars in it anymore they drew the wax so thick. He went back a week later and found 3 or 4 frames of brood. They had a queen, but she's been hard to find. I think he's seen her once since we caught them in may. I'm not sure that's what you're seeing, but it's a thought...