Module-level prep page pagination is off

https://curriculum.codeyourfuture.io/js3/prep/ has two menu items: "how the internet works" and "technical writing 101"

But going to the main page for it it appears to show intro text.

Pressing "next" highlights the menu item "technical writing 101" but shows the content "How the internet works"

Pressing "next" from that page doesn't appear to do anything (but "next" _is_ displayed, which it wouldn't be if there weren't a next page)

It seems like there's a "0. Context" menu item missing or something?