All the minecraft Wikis are out of date when it comes to village mechanics. If you google it, you get results for 1.8 and 1.9 village mechanics as if we're still living in 2014...
I'm pretty sure my villagers are refusing to breed because the population cap is met (hearts appear, beds are accessible, but they go angry mode and give up). This was expected, I'm just testing some breeder designs and the baby villager chamber was too close to the breeding pair. I move them further away but the villagers still won't breed. From the limited info I could find on breeding mechanics:
"A village census is periodically taken to determine the current population"
Okay, great... So what does "periodically" mean? Is it random tick based? On a timer? How long you gotta wait before the population is updated??