3 Months ago I made a bug report about corpses not being visible in Survival Games if you are using Optifine on Minecraft 1.12. The same issue is also on Minecraft 1.12.1 so I assume it will persist on 1.12.2 as well.
Since then I looked into that issue and it seems that it is caused by all corpses having the null character as their name.
While that looks like a bug in Optifine, since it changes the behavior of vanilla minecraft, I'm not sure if they will change it since I don't know of any other server that has this problem. If I'm correct, it would be very simple to fix this by giving the corpses a different name.
So my suggestion that you either change the name or tell me why that won't fix the problem.
On a sidenote I think the mechanic of looting corpses for saturation is bad and should be removed anyway. Most players don't know about it at all, so there are always lots of unlooted corpses around. I personally don't know when it's possible to loot corpses, I've heard that it's only possible for the cannibal kit but I wouldn't know since there is no reason to use any other kit when the cannibal is absurdly overpowered. Additional suggestions: Remove the looting corpses mechanic completely and change the cannibal to only set your hunger to 20 and saturation to 9 instead of giving you the saturation effect on kill.
Since then I looked into that issue and it seems that it is caused by all corpses having the null character as their name.
So my suggestion that you either change the name or tell me why that won't fix the problem.
On a sidenote I think the mechanic of looting corpses for saturation is bad and should be removed anyway. Most players don't know about it at all, so there are always lots of unlooted corpses around. I personally don't know when it's possible to loot corpses, I've heard that it's only possible for the cannibal kit but I wouldn't know since there is no reason to use any other kit when the cannibal is absurdly overpowered. Additional suggestions: Remove the looting corpses mechanic completely and change the cannibal to only set your hunger to 20 and saturation to 9 instead of giving you the saturation effect on kill.