[Tkinter] Tkinter wouldn't work with python3.8.3

[shay_xs]

Hi, I am new to python and Tkinter, I have a very simple code to run see if everything works.

But it seems that it only works with the default python MacBook has, which is Python 2.7
When I try to run it with python 3.8 it only pops out a blank window with a black background.

Here is my code:

import tkinter as tk
window = tk.Tk()
greeting = tk.Label(text="Hello, Tkinter")
greeting.pack()
window.mainloop()

Does anyone know why I am having this problem?
Thanks in advance