Plugin Help Prefilled Chests - nonOP

Hi there.
I have problem.

I wanted to create prefilled chests as a reward for players. So, I have prefilled chest i my invetory. If I place this chest I can see stuff in it. But if it do player or someone who doesn't have OP, they see only empty chest...

Do you know what the problem might be?

Spigot 1.13.2
Plugins:

Code:

PlaceholderAPI,
ArmorStandTools,
PlugMan,
NametagEdit,
SkinsRestorer,
Arconix,
VoxelSniper,
CoreProtect,
GreatKits,
ClearLag,
AgarthaLib,
AdvancedBan,
Elevator,
WorldBorder,
Votifier,
HeadsPlus,
ProtocolLib,
Multiverse-Core,
VotingPlugin,
FastAsyncWorldEdit,
PermissionsEx,
ServerListPlus,
Vault,
TimeVote,
MassiveCore,
CrazyCrates,
Parties,
MobArena,
CreativeGates,
HolographicDisplays,
Spawners,
MyCommand,
Essentials,
Jobs,
Citizens,
Sentinel,
EssentialsChat,
SuperVanish,
EssentialsProtect,
CombatLogX,
EssentialsSpawn,
AuthMe,
ChestShop,
WorldEdit,
Residence,
RFChairs,
EpicRename,
PhantomSMP,
MinePacks,
UltimateTimber