Hello,
Questions #1: This issue would be related to whichever scheduling plugin you are using or to the core scheduling feature in WordPress and not related to the theme itself. You can try deleting the post and re-creating it. Also, check the Status & Visibility settings for that post.
Question #2: If you made any changes to the theme PHP or CSS files the update will have over-written those changes. Which is why it’s always better to use a child theme. Did you or we make any changes to the files?