Uncomment the schedule line on the 'matching_gifts_sync' process-control job and deploy to start calling the sync every 6 hours.
Chang the process-control job to call the drush civicrm-matching-gifts-employers-check command instead of the cvapi MatchingGifts.sync - the civicrm-matching-gifts-employers-check command calls MatchingGifts.sync under the hood and actually won't pick up the new changes if you call the cvapi command right before.