Riverrat hasn't given us a scenario recently, so I'm going to try.
May 1, planting zone 7, hive is well populated, honey flow is on. Plenty of brood, but some cells, "10 to 15 on each side of each brood frame", is partially uncapped and you can see the head of a white pupa. No discolorization, pupa still alive.
What would be your diagnosis, and what steps would you take?