Why will this script work in Studio test but not in-game? (Text Boxes)

Hey everyone, here is the script that I can get to work in Play Solo test mode but not in the game.

local Seat = script.Parent.Parent

local Controls = Seat.Parent

local Model = Controls.Parent:GetChildren()

local Gui = Seat.Guis.TextGui


Gui.Frame.TextBox.Changed:connect(function(prop)

    if prop == "Text" then

        for i, v in pairs(Model) do

            if v.Name == "CenterCar" or v.Name == "RearCar" then

                v.TxtVal.Value = (Gui.Frame.TextBox.Text)

            end

        end

    end

end)

The part of the script that's giving me the issue is the last paragraph. In-game, when the textbox changes, the v.TxtVal.Value won't change. It works in studio, though. I have a feeling it has to do with filtering, but I'm not sure. Can anyone think of a fix?