Villagers and tamed mobs rapidly despawning

My realms world is losing all of its villagers, tamed horses/wolfs and sheep.   It was a slow loss until very recently where it has become catastrophic. I earlier this week I left my "home" town in the games' morning, a town that had over 40 villagers included 4 I had named with name tags, 4 named sheep and 5 named horses in a pen.  When I returned 5 minutes later at the dusk of the single in game day there was only 1 villager, no sheep and 3 horses remaining in the town.  I played today to try and find zombie villagers to repopulate my town and in the course of play visited another near by town.  While there as I watched the villagers in the second town started to despawn. When ever they would go around a corner/through a door/etc they just would be gone.  I ended up exiting out of the game in a frantic hope that I could save some of the town.