Why doesnt my leaderboard save the stats?

Hello! Your leaderboard should save stats, but, there is one problem:

local DataStore = game:GetService("DataStoreService")
local ds = DataStore:GetDataStore("CashSaveSystem")

game.Players.PlayerAdded:connect(function(player)

    local leader = Instance.new("Folder",player)
    leader.Name = "leaderstats"

    local currency = Instance.new("IntValue",leader)
    currency.Name = "Coins"
    currency.Value = ds:GetAsync(player.UserId) or 0 -- I changed this so if there is a new player, their cash would not equal to 0.
    ds:SetAsync(player.UserId, currency.Value)
    currency.Changed:connect(function()
        ds:SetAsync(player.UserId, currency.Value)
    end)

    local experience = Instance.new("IntValue",leader)
    experience.Name = "Exp"
    experience.Value = ds:GetAsync(player.UserId) or 0 --Same here.
    ds:SetAsync(player.UserId, experience.Value)
    experience.Changed:connect(function()
        ds:SetAsync(player.UserId, experience.Value)
    end)

    local experiencelevel = Instance.new("IntValue",leader)
    experiencelevel.Name = "Level"
    experiencelevel.Value = ds:GetAsync(player.UserId) or 0 -- Also the same.
    ds:SetAsync(player.UserId, experiencelevel.Value)
    experiencelevel.Changed:connect(function()
        ds:SetAsync(player.UserId, experiencelevel.Value)
    end)
end)

game.Players.PlayerRemoving:connect(function(player)
    ds:SetAsync(player.UserId, player.leaderstats.Coins.Value)
    ds:SetAsync(player.UserId, player.leaderstats.Exp.Value)
    ds:SetAsync(player.UserId, player.leaderstats.Level.Value)
end)

Basically what I changed was that if there is a new player, their leaderstats would equal 0. That should work, also, check if API services are enabled. And, about that error, when you are testing in Studio, the data transfer is slower. So, that error is fine.