Your script only looks at the first level of parts, so attachments nested deeper get skipped. By recursively traversing all parts and checking both `attachmentId` and inline `data`, you should be able to download the images correctly.

To fix it, you need to recursively walk through all parts of the message payload and handle both cases (`attachmentId` vs inline `data`).

Try this:

def save_attachments(service, msg_id, payload, save_dir="attachments"):
    attachments = []

    def walk_parts(parts):
        for part in parts:
            filename = part.get("filename")
            mime_type = part.get("mimeType")
            body = part.get("body", {})
            
            if filename and (body.get("attachmentId") or body.get("data")):
                if body.get("attachmentId"):
                    attach_id = body["attachmentId"]
                    attachment = service.users().messages().attachments().get(
                        userId="me", messageId=msg_id, id=attach_id
                    ).execute()
                    data = attachment.get("data")
                else:
                    # Inline base64 data
                    data = body.get("data")

                if data:
                    file_data = base64.urlsafe_b64decode(data)
                    filepath = os.path.join(save_dir, filename)
                    with open(filepath, "wb") as f:
                        f.write(file_data)
                    attachments.append(filename)

            # Recurse into nested parts
            if "parts" in part:
                walk_parts(part["parts"])

    walk_parts(payload.get("parts", []))
    return attachments

(PS: I am new to stackoverflow, so all comments are appreciated)