If a scheduled page has an active publishing workflow on it, here's what happens upon release.

When a page (or blog post) is scheduled, view restrictions are added to the page for the users and groups who can edit pages (or blogposts) according to the space permissions. This is so except if the page was created under an automatic publishing workflow. If so, then the restrictions are limited to workflow participants (namely both page editors and workflow reviewers)

  • If the Release Time occurs and the workflow is not yet complete, then the page continues to be restricted to workflow participants.
  • Similarly, when the workflow is complete before the Release Time, then the page continues to be restricted to workflow participants. 

This means that a scheduled page won't be released if created under an automatic publishing workflow that isn't complete, nor will completing the workflow release the page if it is still subject to being scheduled. This preserves the intent of both the workflow and the release schedule and ensures your content will not be released until both the Release Time occurs and the workflow is completed.