Book content complete within game but missing content in compendium

I'm trying to run CoC The Two-Headed Serpent but I'm running into a weird issue where the book is incomplete when accessed through the compendium but is perfectly fine when accessed in game. My picture below shows how content is "missing", the table of contents it shows is even missing chapters. But when I enter my game I can see all of the chapters of the book, like all of the story bits that I actually need. Also, when I click on the Source link (visible in my screenshot) I'm taken to a "Page Not Found" page. Does anyone with access to this book have the same issue? If anyone has had a similar issue please let me know, and if this is just me being new to Roll20 and overlooking something let me know that too. 

Hi Matthew H.,  If the missing sections are part of an adventure they will not be in the compendium. Adventure details are in the Journal tab (creatures and handouts) and Page toolbar (maps).  Note: some adventure content is going to be in the Compendium, such as when an adventure includes a new player option.  If what I have said does not describe what you are seeing please indicate what is missing from the compendium. 

Gauss, Thank you for your response that helps a lot. Coming from D&D Beyond it’s strange to not have access to adventures as a complete book. I wish there was a better way to “flip” through the adventure contents but I do understand how to view it within the game journal.