Players getting Credits but GUI not updating?

This is the only script that is having issues:

local lib = assert(LoadLibrary("RbxUtility"))
pgui = script.Parent.Parent

script.Parent.Changed:connect(function(val)
    local credittab = lib.DecodeJSON(script.Parent.Value)
    pgui.FrameDesign.Design.Credits.TextLabel.Text = credittab.credits .. " Credits"
end)

I have a JSON string (I'm encoding it in JSON because I was asked to) in PlayerGui named "Creds" under which there is the above script. All the other scripts work fine, and the "Creds" value updates on the payday. This is the only issue.

pgui.FrameDesign.Design.Credits.TextLabel is the TextLabel that I want to display the number of Credits the player has.

This exact script used to function perfectly, but all of a sudden, without making any changes, it has stopped working, and I cannot fathom why.

EDIT 1:

In case you wanted to see it, here is the Payday script:

group = 1051234
lp = script.Parent.Parent
local lib = assert(LoadLibrary("RbxUtility"))

if lp:IsInGroup(group) then
    payday = 3
elseif not lp:IsInGroup(group) then
    payday = 1
end

if lp.userId == 18001656 or lp.userId == 32172098 then
    payday = 25
end

time = 5

while true do
    wait(1)
    time = time - 1
    if time == 0 then
        time = 5
        if lp.PlayerGui.Creds.Value ~= "0" then
            local credittab = lib.DecodeJSON(lp.PlayerGui.Creds.Value)
            credittab.credits = credittab.credits + payday
            lp.PlayerGui.Creds.Value = lib.EncodeJSON(credittab)
        else
            local credittab = {
                credits = payday
            }
            lp.PlayerGui.Creds.Value = lib.EncodeJSON(credittab)
        end
    end
end

EDIT 2:

Here is a script that (is supposed to) keep the Player's Credits on death. Perhaps it is the issue?

local lib = assert(LoadLibrary("RbxUtility"))

game.Players.PlayerAdded:connect(function(p)
    p.Character.Humanoid.Died:connect(function()
        local credittab = lib.DecodeJSON(p.PlayerGui.Creds.Value)
        repeat wait() until p.Character
        wait(1)
        p.PlayerGui.Creds.Value = lib.EncodeJSON(credittab)
    end)
end)