So we had to change our server from normal to peaceful due to an accident which a grinder built up too far and ended up crashing part of the server. We ended up switching to peaceful and clearing the built-up items. However, a large radius of area in which the grinder will crash/freeze the person's game if they get near it even, even though everything was cleared out. We eventually just decided to give up on the area and moved around. I eventually realized that there were no mobs, all the old mobs in farms had despawned, and there was no other living thing. We realized it was peaceful and changed it back to normal, however, nothing spawned still. The other issue was the game mode also switched back to peaceful whenever someone left.