DataStore making all values into one?

So i made a article on this yesterday about saving the build. It worked (thanks guys!). But, there is a big flaw when the DataStore saves the data. It makes all the values I want to save in to one? So that means I can't load the build without it having a error because of the Position value I saved since it add the values up. How can I make the dictionary of values not turn in to one value? Here are the links to the scripts I have:

Save Script: https://pastebin.com/Y2W3kckk

game.ReplicatedStorage.SaveBuild.OnServerEvent:Connect(function(player)
	local partTable = {}
	
	for i, inst in pairs(workspace:GetChildren()) do
		if inst.Name == "BuiltBlock" then
			local position = {
				X = inst.Position.X,
				Y = inst.Position.Y,
				Z = inst.Position.Z
				
			}
			local material = inst.Material
			local color = inst.BrickColor
			local size = inst.Size
			partTable[i] = {Position = position, Material = tostring(material), Color = tostring(color), Size = tostring(size)}
		end
	end
	
	local success, err = pcall(function()
		BuildsDataStore:SetAsync(player.UserId, partTable)
	end)
	
	if success then
		print("Saved player build.")
	elseif not success and err then
		print("Not successful: "..err)
	end	
end)

Load Script:

game.ReplicatedStorage.LoadBuild.OnServerEvent:Connect(function(player)
	local s,e = pcall(function()
		local build = BuildsDataStore:GetAsync(player.UserId)
		for i, tab in pairs(build) do
			local block = Instance.new("Part",workspace)
			block.Name = "BuiltBlock"
			block.Position.X = tonumber(tab.Position.X)
			block.Position.Y = tonumber(tab.Position.Y)
			block.Position.Z = tonumber(tab.Position.Z)
			block.Size = tonumber(tab.Size)
			block.Material = tab.Material
			block.BrickColor = tab.Color
		end
	end)
	if s then
		print("Successfully loaded build!")
	elseif not s and e then
		print("Not successful: "..e)
	end
end)

Error when loaded: Not successful: X cannot be assigned to

Data that was saved in the block tables: https://i.imgur.com/WdY9wr1.png

Please answer my question!! -- DragonSpawner12 :D