I have tried to breed villagers in my world with cheats on for keep inventory, and the baby would spawn in, but when the chunks are unloaded, I come back and the baby has immediately despawned. This happens consitantly. It might have something to do with the fact that the villagers are cured, but otherwise I am very confused as to what is happening. One time though, I managed to never get the baby out of render distance and it grew up and does not despawn. Weird!