Royal jelly is produced primarily by young "nurse" bees. In addition to the honey and pollen that they use as raw materials, they add secretions from their mandibular glands to produce royal jelly. The larger the population of the hive, the more abundant the supply of royal jelly that can be produced. That explains why a strong, well populated hive is the best environment for queen bee production.
During the relatively short period while a hive (or nucleus) is producing queen cells, it is highly unlikely for laying workers to develop. Which leads me to believe that CBT's (reply #2) is the most likely explanation for what you experienced.