Automation is great... until it requires human intervention. On very rare occasions, a scheduled post may fail to be published (credentials change or Twitter/Facebook/LinkedIn's API controller are down).
You will now receive an alert in your Cloud Campaign dashboard, as well as, an email or Slack notification if you have them enabled if a post fails to go out.
Simply click on the alert to retry publishing the content.
You will also receive alerts about outages, scheduled downtime, and anything that is crucial to your success on social media.