fix log file selection for ISM+ modes

        all_log_files = os.listdir(log_dir)

        for mode in self.flat_mode_list:

            for f in all_log_files:

                search_string = re.escape("_{}".format(mode))

                if (

                    re.search("_{}".format(mode), f)

                    re.search(search_string, f)

                    and os.path.splitext(f)[1] == LOG_FILE_EXT

                ):

                    # this is a log file belonging to the ivas_format