How come my DataStore won't save said values needed to be saved?

---###----------[[DESCRIPTION]]----------###---

I've been working on a game and I just recently tested how the DataStore is going and if it works and it turns out it doesn't save at all and I get no error. What is the problem with my DataStore and why won't it save?

---###----------[[UPDATE]]----------###---

I forgot you could test DataStores in studio so I tested it and I got the error "104: Cannot store Array in data store. Datastores can only accept valid UTF-8 characters.", but I have no idea what it means and I don't know what UTF-8 characters are.

P.S. I haven't scripted in about a year and I never really used tables so if I used them wrong please tell me and explain what I got wrong!

---###----------[[SCRIPT]]----------###---

--###----------[[SERVICES]]----------###--
local Players = game:GetService("Players")
local TweenService = game:GetService("TweenService")
local DataStoreService = game:GetService("DataStoreService")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
--###----------[[DATASTORES]]----------###--
local LeaderBoard1DS = DataStoreService:GetDataStore("LeaderBoard1DS")
--###----------[[LEADERBOARD]]----------###--
Players.PlayerAdded:Connect(function(player)
    local leaderstats = Instance.new("Folder", player)
    leaderstats.Name = "leaderstats"
--###----------[[BUXSTATS]]----------###--
    local BuxStats = Instance.new("Folder", leaderstats)
    BuxStats.Name = "BuxStats"
--###----------[[OTHERSTATS]]----------###--
    local OtherStats = Instance.new("Folder", leaderstats)
    OtherStats.Name = "OtherStats"
--###----------[[BUX]]----------###--
    local Bux = Instance.new("NumberValue", leaderstats)
    Bux.Name = "Bux"
    Bux.Value = 10000
--###----------[[GAMEPASSES]]----------###--
    local Gems = Instance.new("NumberValue", leaderstats)
    Gems.Name = "Gems"
--###----------[[KILLS]]----------###--
    local Rap = Instance.new("NumberValue", leaderstats)
    Rap.Name = "Rap"
    Rap.Value = 0
--###----------[[ADDBUX]]----------###--
    local AddBux = Instance.new("NumberValue", BuxStats)
    AddBux.Name = "AddBux"
    AddBux.Value = 50
--###----------[[UPGRADECOST]]----------###--
    local BuxCost = Instance.new("NumberValue", BuxStats)
    BuxCost.Name = "BuxCost"
    BuxCost.Value = 5000
--###----------[[TITLE]]----------###--
    local Title = Instance.new("StringValue", OtherStats)
    Title.Name = "Title"
    Title.Value = ""
--###----------[[CASESPEED]]----------###--
    local CaseSpeed = Instance.new("NumberValue", OtherStats)
    CaseSpeed.Name = "CaseSpeed"
    CaseSpeed.Value = 10
--###----------[[CASESPEEDCOST]]----------###--
    local CaseSpeedCost = Instance.new("NumberValue", OtherStats)
    CaseSpeedCost.Name = "CaseSpeedCost"
    CaseSpeedCost.Value = 25000
--###----------[[MULTIPLIER]]----------###--
    local Multiplier = Instance.new("NumberValue", OtherStats)
    Multiplier.Name = "Multiplier"
    Multiplier.Value = 1
end)
--###----------[[LEADERBOARDDS/DATASTORES]]----------###--
Players.PlayerAdded:Connect(function(player)
    local PlayerGui = player:WaitForChild("PlayerGui")
    wait()
    local plrkey = "id_"..player.userId
    local LeaderStats = {
        LeaderStats1 = player.leaderstats.Bux,
        LeaderStats2 = player.leaderstats.Gems,
        BuxStats1 = player.leaderstats.BuxStats.AddBux,
        BuxStats2 = player.leaderstats.BuxStats.BuxCost,
        OtherStats1 = player.leaderstats.OtherStats.CaseSpeed,
        OtherStats2 = player.leaderstats.OtherStats.CaseSpeedCost
    }

    local GetSaved = LeaderBoard1DS:GetAsync(plrkey)
    if GetSaved then
        LeaderStats.LeaderStats1.Value = GetSaved[1]
        LeaderStats.LeaderStats2.Value = GetSaved[2]
        LeaderStats.BuxStats1.Value = GetSaved[3]
        LeaderStats.BuxStats2.Value = GetSaved[4]
        LeaderStats.OtherStats1.Value = GetSaved[5]
        LeaderStats.OtherStats2.Value = GetSaved[6]
    else
        local NumberForSaving = {
            LeaderStats.LeaderStats1.Value,
            LeaderStats.LeaderStats2.Value,
            LeaderStats.BuxStats1.Value,
            LeaderStats.BuxStats2.Value,
            LeaderStats.OtherStats1.Value,
            LeaderStats.OtherStats2.Value
        }
        LeaderBoard1DS:SetAsync(plrkey, NumberForSaving)
    end
end)
Players.PlayerRemoving:Connect(function(player)
    LeaderBoard1DS:SetAsync("id_"..player.userId, {player.leaderstats.Bux.Value, player.leaderstats.Gems.Value, player.leaderstats.BuxStats.AddBux.Value, player.leaderstats.BuxStats.BuxCost.Value, player.leaderstats.OtherStats.CaseSpeed, player.leaderstats.OtherStats.CaseSpeedCost})
end)