The issue seems to be with how the find_zip_files function is structured. It initializes zip_files with None values for each key (vte, cli, art), and if a file matching one of these criteria is not found in the folder, it remains None. Later in your code, you're checking if zip_files["vte"], zip_files["cli"], or zip_files["art"] are None to decide whether to skip processing for that month.

Given that your code is skipping all files, it suggests that it's not finding files that match the expected criteria ("VTE", "CLI", "ART"). This could happen due to several reasons:

Case Sensitivity: Python string operations are case-sensitive. If the filenames in your directory are not exactly "VTE", "CLI", "ART" (e.g., they are lowercase or mixed case), they won't match the checks in find_zip_files.

File Extension: The function find_zip_files checks for filenames ending with .zip. If your files have different extensions or no extension, they won't be recognized.