After submitting this question, the images started to show up in the bucket. Possibly I was not patient enough or you did something in the background. The only change that I have made is to switch from S3 Amazon to Default in the Copy AI Generated images dropdown and then back to S3 Amazon. Not sure which of these actions made a different.
However, the featured images in the post are still referencing the local images and not the once on Amazon. But I will spend some time testing now, as I have copies availble in the bucket.