How to make progress bar work using PySimpleGUI in Python?

I am using PySimpleGui's one-line progress meter to show the files processed while my main function is running. It is working for the most part, however when I change the parameter from value of 1000 to my variable total_files it just flickers and never stays on screen. It's only when I keep the parameter to a value of 1000 does the screen stay put...but I want to just show the progress of the true amount of files processed.

For example, I have 8 files I am processing as a test. I want the progress bar to stay on the screen and just show those 8 files processed. Does anyone know what I'm doing wrong?

Documentation on progress meter:
https://www.pysimplegui.org/en/latest/#progress-meters

for i in range(1,total_files):
    sg.one_line_progress_meter('Loading...', i+1, 1000, 'key','Files Processed', orientation="horizontal")

Below is my code:

import PySimpleGUI as sg, pandas as pd, os, time
from pathlib import (
    Path,
)


def convert_to_csv(input_folder, output_folder, dataframe2, dataframe3):
    start = time.time()
    # Parentsupplierbrand mapping file. Change the filepath to where the file is stored on your computer.
    df2 = pd.read_csv(rf"{dataframe2}", sep="|")
    # KCS Section Codes mapping file. Change the filepath to where the file is stored on your computer.
    df3 = pd.read_excel(rf"{dataframe3}")
    # loop through only text files in the input folder and convert data
    for files in os.listdir(input_folder):
        if files.endswith(".txt"):
            df1 = pd.read_csv(rf"{input_folder}/{files}", sep="\t", encoding="latin-1")

            df1["BrandName"] = df1["Comp_Brand"].apply(
                xlookup, args=(df2["BrandID"], df2["BrandName"])
            )
            # map columns to the desired headers
            df1.rename(
                columns={
                    "BrandName": "Competitor_Name",
                    "Comp_PN": "Competitor_PartNumber",
                    "CQ_Brand": "AAIA_Code",
                    "CQ_PN": "PartNumber",
                },
                inplace=True,
            )
            remove_columns = df1.loc[
                :, ~df1.columns.isin(["Comp_Brand", "CQ_Desc", "PartID"])
            ]
            new_columns = [
                "Competitor_Name",
                "Competitor_PartNumber",
                "AAIA_Code",
                "PartNumber",
            ]
            table_output = remove_columns[new_columns]

            # below code for constructing file name convention
            kcs_section_codes = df3.values.tolist()
            stringtwo = table_output.loc[0][2]  # stringtwo is the AAIA_Code
            for code in kcs_section_codes:
                if code[0] == stringtwo:
                    # stringone is the matching value under BrandName in the KCS_Section_Codes file
                    # by looking up AAIA_Code from the initial file in the BrandCode column from the KCS_Section_Codes file
                    stringone = "".join(
                        e for e in code[1] if e.isalnum()
                    )  # replace any character that is not a letter or number with an empty character.

            filename = rf"{stringone}-{stringtwo}_Interchanges.txt"

            outputfile = rf"{output_folder}/{filename}"

            table_output.to_csv(
                outputfile,
                sep="\t",
                index=False,
                columns=[
                    "Competitor_Name",
                    "Competitor_PartNumber",
                    "AAIA_Code",
                    "PartNumber",
                ],
            )
            # progress bar
            total_files = sum([len(files) for r, d, files in os.walk(output_folder)])
            for i in range(1, total_files):
                sg.one_line_progress_meter(
                    "Loading...",
                    i + 1,
                    1000,
                    "key",
                    "Files Processed",
                    orientation="horizontal",
                )
    # code below for returning stats of main function in a popup window
    total_files = sum([len(files) for r, d, files in os.walk(output_folder)])
    end = time.time()
    result_time = end - start
    time_formatted = time.strftime("%H:%M:%S", time.gmtime(result_time))
    sg.popup_no_titlebar(
        f"Done! :)\nTotal Files Processed: {total_files}\nExecution Time (hh:mm:ss): {time_formatted}"
    )


def xlookup(lookup_value, lookup_array, return_array, if_not_found: str = ""):
    match_value = return_array.loc[lookup_array == lookup_value]
    if match_value.empty:
        return f'"{lookup_value}" not found!' if if_not_found == "" else if_not_found
    else:
        return match_value.tolist()[0]


def is_valid_path(filepath):
    if filepath and Path(filepath).exists():
        return True
    sg.popup_error("Filepath not correct")
    return False


def gui():
    sg.theme("DarkBlue3")  # Add a touch of color
    # All the stuff inside your window.
    layout = [
        [
            sg.Text("Input Folder: "),
            sg.Input(key="-IN-"),
            sg.FolderBrowse(),
        ],
        [sg.Text("Output Folder: "), sg.Input(key="-OUT-"), sg.FolderBrowse()],
        [
            sg.Text("Data Mapping File: Parent Supplier Brand"),
            sg.Input(key="-DF2-"),
            sg.FileBrowse(),
        ],
        [
            sg.Text("Data Mapping File: KCS Section Codes"),
            sg.Input(key="-DF3-"),
            sg.FileBrowse(),
        ],
        [sg.Exit(), sg.Button("Convert to CSV")],
    ]

    # Create the Window
    window = sg.Window("Data Conversion", layout)

    # Event Loop to process "events" and get the "values" of the inputs
    while True:
        event, values = window.read()
        if (
            event == sg.WIN_CLOSED or event == "Cancel"
        ):  # if user closes window or clicks cancel
            break
        if event in (sg.WIN_CLOSED, "Exit"):
            break
        if (
            event == "Convert to CSV"
        ):  # if user clicks covert to csv button then call convert_to_csv function using inputs
            if (is_valid_path(values["-IN-"])) and (is_valid_path(values["-OUT-"])):
                convert_to_csv(
                    input_folder=values["-IN-"],
                    output_folder=values["-OUT-"],
                    dataframe2=values["-DF2-"],
                    dataframe3=values["-DF3-"],
                )
    window.close()


if __name__ == "__main__":
    gui()

Following code update the progressbar without any time delay, so it will show in short time and reach the maximum value immediately, then the window for progressbar closed.

            for i in range(1, total_files):
                sg.one_line_progress_meter(
                    "Loading...",
                    i + 1,
                    1000,
                    "key",
                    "Files Processed",
                    orientation="horizontal",
                )

Reduce your code to ask question, it will help people to help.

Demo code:

from time import sleep
import PySimpleGUI as sg
from threading import Thread


def job(window):
    window.write_event_value("Update", 0)
    for i in range(1, 11):
        sleep(0.2)                              # Simulate each step in the job
        window.write_event_value("Update", i)   # Cannot update GUI not in the main thread
    window.write_event_value("Done", None)

sg.theme("DarkBlue3")

layout = [[sg.Button("Submit"), sg.Button("Exit")],]
window = sg.Window("Title", layout)

while True:

    event, values = window.read()

    if event in (sg.WIN_CLOSED, "Exit"):
        break
    elif event == "Submit":
        thread = Thread(target=job, args=(window, ), daemon=True)
        thread.start()
    elif event == "Update":
        i = values[event]
        sg.one_line_progress_meter("Loading...", i, 10, "key", "Files Processed", orientation="horizontal")
    elif event == "Done":
        print('Job done !')

window.close()