package com.teraxus.mod.events;

import java.util.Random;

import com.teraxus.mod.init.ModItems;

import net.minecraft.entity.passive.EntityBat;
import net.minecraftforge.event.entity.living.LivingDeathEvent;
import net.minecraftforge.fml.common.Mod.EventHandler;
import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;

public class BatDeathEvent {

@SubscribeEvent
public void onBatDeath(LivingDeathEvent event)
{
	if(!(event.getEntity() instanceof EntityBat))
	{
		return;
	}
	else
	{
		EntityBat bat = (EntityBat) event.getEntity();
		Random rand = new Random();
		int randomInt = rand.nextInt(2) + 1;
		bat.setDropItemsWhenDead(false);
		bat.dropItem(ModItems.rawBat, randomInt);
	}
}
}

 

When I kill a bat, it drops 2-5 items. ~40% of the items can be picked up, and the others cant be picked up. Why does this happen?

Because you're also spawning those items on the client side which don't actually exist. If you log out and log back in again, they'll be gone.