I have a 'U' villager trading hall, approximately 20x20 blocks, converted from a previous version. Villagers are seperated by profession and each is provided with a bed.  As a villager grows up, I add a workstation and trap them in their section. As I made it around the horizontal bar of the 'U', suddenly the villagers stopped recognizing new beds and would not breed. I ensured they were provided with food and it continued to happen.

After a bit of experimenting, the same behavior occurred with workstations.