MarketPlaceService + Data Store script not functioning 100%

In the startpack I have a localscript with this:

local productId = 19186931
plr = game.Players.LocalPlayer
plrgui = plr:WaitForChild("PlayerGui")

plrgui.ChildAdded:connect(function(child)
if child.Name == "EndGui" then
	wait()
	buyButton = script.Parent.Parent.PlayerGui.EndGui.Continue
	buyButton.MouseButton1Click:connect(function()
	if buyButton.Visible == true then
	Game:GetService("MarketplaceService"):PromptProductPurchase(game.Players.LocalPlayer, productId)
	end
end)
	end
end)

This script seemingly works perfectly. It fires the transaction, so that's all good! It's the server side script in Workspace that seems to have problems.

This is the server script:

local MarketplaceService = Game:GetService("MarketplaceService")
local productId = 19186931
local ds = game:GetService("DataStoreService"):GetDataStore("ContinueButton")

function GetPlayerById(id)
	for _,v in ipairs(game.Players:GetPlayers())do
		if(v.userId==id)then
		return(v) 
		end
	end
	return(nil)
end

MarketplaceService.ProcessReceipt = function(receiptInfo)
	if receiptInfo.ProductId == productId then
	local asynccode = receiptInfo.PlayerId .. "buys"
		if ds:GetAsync(asynccode) == nil then
			ds:SetAsync(asynccode, 0) 
		end
	ds:IncrementAsync(asynccode, 1)
	print("Player bought the continue developer product. Player now has "..ds:GetAsync(asynccode).." buys.")
	
	currentplr = GetPlayerById(receiptInfo.PlayerId)
	
	gui = currentplr.PlayerGui
	gui.continuegame.Disabled = false
	
	return Enum.ProductPurchaseDecision.PurchaseGranted		
	end
	end

I have tried using both ROBLOX remote error and Obox checking system but neither print any of the prints I have and neither display any errors.. But it doesn't work!

What's wrong? If you can offer a solution to the debugger that'd be even better!

(P.S. you could have edited the old question rather than make a new one)

Try changing line 17 in the Script to this:

if not (ds:GetAsync(asynccode) or false) then 

If that doesn't work, try using a RemoteFunction to call the PromptProductPurchase from the Script instead of the LocalScript.