If one is clearing and one is not, then the add-on functionally is working, e.g. no known or obvious bugs. There is something _very_ specific going on for the site that is not clearing, and since you’re using file it leads me to believe that it has to be a permission error and it’s unable to delete the cache file. The next step is to debug the CacheBreaker.php->_breakEntryCache() function to see if anything is going wrong in that function. If you can var_dump, step debug, or log that function it might reveal something. Have you checked your php error logs? B/c it will try to log an error if it exists. At the bottom of that function is this:

try {
            if (count($clear_tags)) {
                $this->clearTags($clear_tags);
            }

            if (count($clear_items)) {
                $this->clearItems($clear_items);
            }

            if (count($refresh_items)) {
                $this->refreshItems($refresh_items);
            }
        } catch (\Exception $exception) {
            error_log($exception->getMessage());
        }