Despawn of Mobs

Hy everyone, in the world that I have with my friends we are having difficulties, with the mobs and redstone circuits, the mobs disappear despite having a nametag, and the redstone circuits stop working from scratch (it is necessary to update them with a block). I have searched other threads for information about all this but I can't find anything

I share the log, but I don't think that is very useful to this case https://mclo.gs/01n8h9S