Wargada

As I said in my first comment, in my case, the disappearances didn't happened after any restarting, but during gameplay, with severals players on my servers connected with me !

So yes, I also noticed that happened on a multiplayer server, but not after restarting (in my case).

Today I tried to create the same situation, which happened on my server (creating fortress with bell, beds, lights, jobs blocks and 2 villagers). I let the game turn during 1 hour, was afk away from the fortress and already no disappearances... I continue tomorrow to see after 3 hours, like @@unknown said.

One the other hand, others disappearances continue happening on my server !!! 

Same problem, I had a little castle with 6 villagers, all with "job" and connected with their "job block", I never trade with them or named them, they all had beds for sleeping, there was a bell in the castle, and lights everywhere, a golem and 2 cats spawned naturally around the castle.

For severals Minecraft days there wasn't any problem, but one day only 1 villager left in the castle (the first I moved in the castle I think), so I went outside to check if the golem was still here, and no, golem and cats were disappeared too, and when I came back in the castle, the only villager left was disappeared.... All in the same session, without restart or quit the server ! 

I tried to explain the better I can as @violine1101 said in an other ticket, but sorry for my english, I'm really bad (I'm french, sry ! haha)