Update variable from imported module with Python when using Threading

In a project, I would like to separate the visualization and calculation in two different modules. The goal is to transfer the variables of the calculation-module to a main-script, in order to visualize it with the visualization-script.

Following this post Using global variables between files?, I am able to use a config-script in order to transfer a variable between to scripts now. But unfortunately, this is not working when using threading. The Output of the main.py is always "get: 1".

Does anyone have an idea?

main.py:

from threading import Thread
from time import sleep

import viz

import change
add_Thread = Thread(target=change.add)
add_Thread.start()

viz.py:

import config

from time import sleep

while True:
    config.init()
    print("get:", config.x)
    sleep(1)

config.py:

x = 1

def init():
    global x

change.py:

import config

def add():
    while True:
        config.x += 1
        config.init()