Ah, sorry I forgot to attach the screenshot link. And yes, this is a new install.
Here’s where it appears, below the header and above the article title:
View post on imgur.com
Strangely, it’s the only thing that gives us trouble. We can position a comment section/share bar where we want it below the article, but the related posts always appears at the top.
I was able to position it exactly where desired with Twenty Sixteen. So perhaps this is a theme issue.