DataStore only occasionally saving/retrieving data?

So, I asked a question a day or two ago, about my DataStore not working. Well, it works now, but only occasionally.

I'm not sure what to do, because I don't wanna completely break it again, so I came here. If anyone can help, I'm new to scripting so it would be appreciated. Here's my code:

local dataStoreService = game:GetService("DataStoreService")
local StatStore = dataStoreService:GetDataStore("DataStats")

game.Players.PlayerAdded:Connect(function(player)
    game.Workspace:WaitForChild(player.Name)
    player:WaitForChild("leaderstats")
    player.PlayerGui.Codes.SpeedBoost.Parent = player

    local Key = player.UserId

    local Leaderstats = player.leaderstats
    local Steps = Leaderstats.Steps
    local SpeedBoost = player.SpeedBoost

    local DefaultSteps = 0

    local DefaultData = {
        0,
        false
    }

    local Stats = {
        Steps.Value,
        SpeedBoost.Value
    }

    local NewStats
    local recieved, notRecieved = pcall(function()
        NewStats = StatStore:GetAsync(Key)
    end)

    if recieved then
        Steps.Value = NewStats[1]
        SpeedBoost.Value = NewStats[2]
        print("Stats were recieved")
        wait(1)
        StatStore:SetAsync(Key, Stats)
    else
        StatStore:SetAsync(Key, DefaultData)
        print("Stats were not recieved")
        warn(notRecieved)
    end

    wait(0.1)

    while wait(10) do
        local saved, notSaved = pcall(function()
            StatStore:UpdateAsync(Key, function(oldValue)
                return Stats
            end)
        end)

        if saved then
            print("Stats were auto saved!")
        else
            print("Stats didn't auto save.")
        end
    end
end)

game.Players.PlayerRemoving:Connect(function(player)
    local Key = player.UserId

    local Leaderstats = player.leaderstats
    local Steps = Leaderstats.Steps
    local SpeedBoost = player.SpeedBoost

    local DefaultData = {
        0,
        false
    }

    local Stats = {
        Steps.Value,
        SpeedBoost.Value
    }

    local success, result = pcall(function()
        StatStore:UpdateAsync(Key, function(oldValue)
            return Stats
        end)
    end)

    if success then
        print("Stats were saved!")
    else
        print("Stats were not saved.")
        warn(result)
    end
end)

Sorry if it's messy, like I said, I'm new to scripting.

Steps is an IntValue and SpeedBoost is a BoolValue.