It shows up on your "Quiet and Privacy" listing, @John143. Here is a screenshot. I don't see a guidebook on your other listings. I don't know how much you know about guidebooks, but you do have to create one for each listing. If you know that, and they have just disappeared, I understand your frustration. The online guidebook drove me crazy until I decided to ignore it.
Just not showing up when I try to change it. My property is at Julian Cabins where I list guest book items too. I will call tech support. I think it is a bug