Scheduled posts do not publish. When the time for publishing is reached WP reschedules the post for a future time.
For example, I had a post that the post manager said was scheduled to be published in 28 minutes. I looked again in 30 minutes and the manager now said the post was scheduled to be published in two hours.
It just keeps going like this. Whenever the time to publish is reached more time is added and the post is never published.