I had several villagers die in a zombie raid.  4 villagers remain in the village.  When I drop bread right on them they do not pick it up.  I have left crops (carrots) in their farms.  The farmers do not harvest them when ripe, and make no attempt to pick them up when I break the crops.  I stayed in my village several days, there are plenty of vacant beds, but they won't breed or take the food they need to breed.