Problem/Bug FULL Item loss on death (not in inventory, not in the workspace)

Hello, i'm holding a modded server.

There's a problem which is when people die, they don't keep stuff in their inventory and the stuff isn't dropped.
(Verified : Clearlag isn't the issue, Not any mod has a gravestone feature, keepInventory has ever been in false)

Mods list :

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Anger Management;
Baubles;
BetterFPS;
Blocklings;
Bloodmoon;
Draconic Evolution;
Extreme Reactors;
Industrial Craft 2;
InventoryTweaks;
IronChest;
JustEnoughItems;
Mantle;
Mekanism;
NotEnoughItems (jei addon);
Pam's Harvestcraft;
Primitive Mobs;
Real Survivor;
Redstone Flux;
Realm Of The Dragons;
Thaumcraft;
Tinker's Construct;
Tough As Nails;
Twilight Forest;
Useful Backpacks.

Including of course libraries, cores and other requires/dependencies for the mods.

Plugins list :

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AmkMcAuth;
ChestShop (& ChestShop LegacyIds);
ClearLag;
CoreData;
CorePlaytime;
CoreProtect;
CPSAlert;
EasySetSpawn;
Essentials;
EssentialsAntiBuild;
EssentialsChat;
EssentialsSpawn;
GroupManager;
iConomy;
Images;
KillerMoney;
mclo.gs;
NoCheatPlus;
sTablist;
StaffTools;
SuperVanish;
TimeIsMoney;
Vault;
VladeScoreboard;
WarnSystem;
WorldEdit;
WorldGuard;
XPBoost
xRay;
XrayInformer.

Thanks for your help!