Literally every single one of my passive entities is gone. All of the cows out of my cow pasture, gone. All of my saddled horses were gone out of my horse stable. All of my librarian villagers that I had a cured and locked in trades with, gone. The villages were also named tagged as well as so I knew which villager was trading what trade. And when I went into my house, all of my pets that were also name tags, gone. The sheep out of my wool farm had all disappeared as well, and the hopper mine cart that ran under them was missing also. And it is a reoccurring issue because after my villagers disappeared, I needed to cure another zombie villager so I could get a mending book, and I finally got a mending trade, and when I log back onto the game, that one was gone also.

I added a couple pictures to show that all of the sheep are gone out of my wool farm, all of the pens are empty in my horse stable, the fence is empty where I held my cows, The house is empty that originally had three librarian villagers in it, and when they disappeared I added a mending villager who also disappeared. I also added a photo of my CD farm, so you can see that my skeleton disappeared also, which was also name tagged. So it isn't just passive mobs that are disappearing. It is all mobs. And I also added a photo of under my sheep farm so you can see that my hopper mine cart has disappeared also. I looked in all hoppers and chests, and it's not in there. 

also- I edited to add, this is the first time I’m reporting one of these, so some of the information may not be correct. I don’t think it was a bedrock dedicated server, I don’t play on a server. I play bedrock edition of Minecraft, but I just play in my own world. Not a specific server.