I have a world ive been playing on since last summer. Id found a few villages around the area i chose to build my house. When the bedrock update came to ps4 and i converted my world i went to one of the villages and they were all gone. Before the update there were at least 10 villagers. I made my own village across the river from my house, and went to find zombie villagers to cure. I gave them nametags so they wouldnt despawn. I brought them back to the village i created and assigned them to jobs. I built some golems and put a wall around them so they wouldn't be easily taken out by mobs and illagers, but then after i quit playing for a bit i got on the game went to trade with them and one villager and golem complely disappeared.  Theres no way they could have gotten over the stone walls. So i went and got 2 more zombies cured, did the same thing and now the villager that was still there after the other one disappered, has disappeared too. They all had nametags. I feel like i was just wasting time curing zombies and giving them their own place because they keep disappearing.