Any unpublished images are automatically published when a story in Composer is published or scheduled to publish at a later time. However, if new unpublished images are added to the Composer file later (after the story is scheduled, but before it is actually live), those images are not published when the article is saved nor when it turns live, so they do not appear in the article
Emily Babay
Hello, thank you for submitting this idea! You raise a very good point: today, when a story is scheduled to publish, any unpublished images that are included in the story at the moment you schedule publication are published once the story publication is scheduled. For any unpublished images added to a story after "schedule publish," those are not automatically published, because we're changing the image publication status at the moment you schedule publish. But it would make sense that we should be rolling those images forward to a published status so long as you've saved that story as the most recent version scheduled to publish.
In the meanwhile, before we have that in place, I would recommend one of two workarounds: (1) ensure that all images you're adding to scheduled stories are already in published status or (2) unschedule and re-schedule the story to publish, so you can ensure the new images are included and published.