I recently had a problem of a similar nature, and spent hours looking for the queen, and couldn't find her. So I combined with a nuc that had a marked queen in it, which was killed within a day. So I broke the hive into three nucs, and gave the two that I thought the queen wasn't in, queen cells. The one that I thought the old queen was in, didn't get one, and one of the ones that did get a queen cell, tore it down. Anyway I can only surmise that the queen in the orginal hive quit laying or was a virgin. Because that hive now has lots of eggs and capped brood.
"I reject your reality, and substitute my own." Adam Savage