So in the lastest snapshot I am running a server with friend and thier is a spawning glitch happening and mobs wont spawn unless I restart the server.

This is at least partially happening in single player games, as well, and reloading doesn't help.

So far, what I've seen is FISH missing, and now I've just been discussing with a friend, the fact that she hasn't seen a single GUARDIAN of any type, in the monument she's been renovating.

Duplicate of MC-139338.