Thank you for taking the time to inform us of the `_posts` issue occurring in this course. We have been looking into it and have pushed up a change that now allows the posts to be displayed on the homepage. We were using a jekyll theme that didn't handle posts as instructed in the course steps, and for this we apologize for the inconvenience.
For the fix, we made a change to the instructed theme but are currently evaluating several other themes and slight modifications to the course steps/logic to improve the end-of-course deliverable.
From here, there are several options you can take to remedy your existing repository.
You can change the theme in your `_config.yml` file to read `theme: minima` and that will update your GitHub Pages site with a theme that will display your posts.