Disappearing Villages

HI, I created a village in Creative mode, populated it with villagers. After i had finished and they took on the roles like Mason and Farmer etc, and went to their beds, I exited the game. When i reloaded it, the villagers had disappeared completely, there were no holes or fissures for them to drop into and there was a protective wall around the village which was well lit and therefore no hostile mobs could spawn in. I tried repopulating the village and the new people didnt take on the roles as before and they wouldnt go to a bed - they just clustered around a building saying "hhmm". Every time I come out and go back in, the villagers have disappeared. This has on;y started happening with this new snapshot. The world was created in the new snapshot, it is not from a previous version.