Right now, I can’t seem to add new page sections. The pages are created (I can preview them) but they don’t show up on my single page view, even after checking the appropriate boxes in the Theme Options.
For going back to the original page section, you need the menu with URL like this – http://yoursite.com/#page-section-slug. I can explain this here but can you pls check the first section of the documentation which explains it more clearly with screenshots.
In your case, you just need to prefix the menu URLs pointing to these sections with the page URL. If it is home page, you would have the home page URL or else, it would be something like http://yoursite.com/home-page-2/#page-section. Just specifying #page-section leads to the issue you mention above.
Pls check the One Page Menu that I have modified in your case for the change made. Hope this helps.