Why won't my GUI Text Update?

Mtext = game.StarterGui.ScreenGui.MainText
minigames = game.Lighting.Minigames:GetChildren()



function removePlate()
	local plates = game.Workspace.DissapearingPlates.Plates:GetChildren()
	local ranNum1 = math.random(1, #plates)
	local ranNum2 = 1
	while ranNum1 == ranNum2 do
		ranNum2 = math.random(1, #plates)
		wait()
	end
	local plateChosen = plates[ranNum1]
	local plateChosen2 = plates[ranNum2]
	for i = 0, 1.5, .05 do
		plateChosen.Transparency = i
		plateChosen2.Transparency = i
		wait()
	end
	plateChosen:Destroy()
	plateChosen2:Destroy()
end

while true do

	if game.Players.NumPlayers >= 2 then
		Mtext.Text = "Choosing a random map..."
		wait(7)
		ranGame = math.random(1, #minigames)
		gameChosen = minigames[ranGame]
		Mtext.Text = "Minigame Chosen: "..gameChosen.Name
		wait(3)
		gameChosenClone = gameChosen:Clone()
		gameChosenClone.Parent = game.Workspace
		wait(3)
		--teleport
		spawns = gameChosenClone.Spawns:GetChildren()
		for i,v in pairs(game.Players:GetPlayers()) do
			name = v.Name
			check = game.Workspace:FindFirstChild(name)
			if check then
				checkhumanoid = check:FindFirstChild("Humanoid")
				if checkhumanoid then
			v.Character:MoveTo(spawns[i].Position)
			v.InGame.Value = true
				end
			end
		end
	
			if gameChosenClone.Name == "DissapearingPlates" then
				for i = 5, 1, -1 do
				Mtext.Text ="Game begins in: "..i
				wait(1)
				end
				
		time = 25
		--countdown
		for i = time, 0, -1 do
			Mtext.Text = "Time left: "..i
			removePlate()
		end
	end

		Mtext.Text = "Game Ended!"
		wait(3)
			gameChosenClone:Destroy()
	else
		Mtext.Text = "There needs to be 1 more player to start"
		
			end
		wait(1)
		
		end

No error in output either

Just to clarify, StarterGui is only a container. When a game runs all of StarterGui is copied and pasted into PlayerGui. You need to update PlayerGui for the player to see the changes.