Why isn't this DataStore script working correctly?

I'm trying to get my DataStore script to automatically detect all the stats in the player's stats folder, as there are many, and save/load them all accordingly. For some reason however, it's either not saving correctly or not loading correctly. When I run the game, set the values of the stats, then leave, when I rejoin all of them are back to their default values instead of the ones that should have been saved.

local dataStore = game:GetService("DataStoreService")
local players = game:GetService("Players")

local statsStore = dataStore:GetDataStore("StatsStore")

function playerAdded(player)
	local playerGui = player:WaitForChild("PlayerGui")
	local statsGui = playerGui:WaitForChild("StatsGui")
	local playerStats = statsGui:WaitForChild("PlayerStats") --the folder where all the player's stat values are stored
	
	local key = ("player_"..player.UserId)
	
	local savedStats = statsStore:GetAsync(key)
	
	local statsToSave = {}

	for _, playerStat in pairs(playerStats:GetChildren()) do
		statsToSave[playerStat.Name] = playerStat.Value
	end

	if savedStats then
		for statName, stat in pairs(savedStats) do
			local playerStat = playerStats:FindFirstChild(statName)
			if playerStat then
				playerStat.Value = stat
			end
		end
	else
		statsStore:SetAsync(key, statsToSave)
	end
end

function playerRemoved(player)
	local playerGui = player:WaitForChild("PlayerGui")
	local statsGui = playerGui:WaitForChild("StatsGui")
	local playerStats = statsGui:WaitForChild("PlayerStats")
	
	local key = ("player_"..player.UserId)
	
	local statsToSave = {}
	
	for _, playerStat in pairs(playerStats:GetChildren()) do
		statsToSave[playerStat.Name] = playerStat.Value
	end
	
	statsStore:SetAsync(key, statsToSave)
end

players.PlayerAdded:connect(playerAdded)
players.PlayerRemoving:connect(playerRemoved)