I have the same exact code twice, why does the server only copy over the instances of one?

Basically, im reworking a localscript to work on the server for a game im creating. What I have set up is a function that takes an instance, sends it to the client to identify and get certain client-only properties (such as absolutesize and absoluteposition), and send it back. The code is here:

serverscript:

function GetAbsolutePosition(instance2)
    print(instance2)
    game.ReplicatedStorage.Events.GetAbsolutePosition:FireClient(Player, instance2)
    local AbsolutePosition = nil;

        game.ReplicatedStorage.Events.ReturnPosition.OnServerEvent:connect(function(player, AbPosition)
            print("Got Result")
            AbsolutePosition = AbPosition
        end)

        while true do
            if AbsolutePosition ~= nil then
                return AbsolutePosition
            end
            wait()
            if AbsolutePosition ~= nil then
                break;
            end
            wait()
        end
end

localscript:

spawn(function()
    game.ReplicatedStorage.Events.GetAbsolutePosition.OnClientEvent:connect(function(instance)
        print(instance.ClassName)
        game.ReplicatedStorage.Events.ReturnPosition:FireServer(instance.AbsolutePosition)
    end)
end)

The above code currently works. I modified it to also get the absolute size of the GUI object, but this time on the client side, it gives a nil instance error. Server Size Code:

function GetAbsoluteSize(instance)
    print(instance.ClassName .. " Is Sizing")
    if instance == nil then
        print("NIL INSTANCE NHJSHBJFBHJKBKHJSFKBHJSFKBHJFSBKHJ")
    end
    game.ReplicatedStorage.Events.GetAbsoluteSize:FireClient(Player, instance)
    local AbsoluteSize = nil;

        game.ReplicatedStorage.Events.ReturnSize.OnServerEvent:connect(function(player, AbSize)
            print("Got Result")
            AbsoluteSize = AbSize
        end)

        while true do
            if AbsoluteSize ~= nil then
                return AbsoluteSize
            end
            wait()
            if AbsoluteSize ~= nil then
                break;
            end
            wait()
        end
end

LocalScript:

spawn(function()
    game.ReplicatedStorage.Events.GetAbsoluteSize.OnClientEvent:connect(function(instance2)
        print(instance2.ClassName .. " has reached renderstepped")
        game.ReplicatedStorage.Events.ReturnSize:FireServer(instance2.AbsoluteSize)
    end)
end)

The two are practically the same code, so im very confused on why the bottom one does not work. I've tried almost everything I know at this point, and nothing seems to work.