The males will move in first and stay longer then the female. She will move in and out to lay her eggs. A similar situation happened last few weeks to me with this cold snap.
The males moved on the bed and a few females started to come up and lay. Well I believe the cold snap pushed the females back off but the males remained to look after the nest. This past week with warmer temps the females were back and all was good.
Another theory: They already laid the eggs and the males are still up there gurding the nest and the females are long gone.
Keep after them,