Customizing option has disappeared

Until recently, I had the option to edit the contextual related posts right from the blog post. There was a link to “Edit related posts” that allowed me to choose my own related posts instead of depending on the random selection I’m stuck with now.

Sometimes, the related posts make sense, but often they don’t (as in the post I linked to). I miss being able to pick and choose the best related posts. Is that still an option for me? If so, why am I no longer seeing it?

The page I need help with: [log in to see the link]