Hi Dominic
I made the change to content.post.header.php in the layouts folder of my child theme as you suggest and it does not fix the issue.
After the recommended php change, when post sidebar information is enabled I see the meta data date, author leave reply as well as the sidebar information that shows categories, permalink, tags and author avatar.
Disabling post sidebar information disables ALL the above information including meta data date, author and leave reply despite being enabled on the post.
To recap, I want to see meta data date, author and leave reply. I do not want to see the sidebar information.
Thanks