Role cannot create or edit book content I feel like I am missing something obvious that I just can't quite put my finger on.

As an administrator, I see "Add Content > Book page" and "My Workbench > Create Content > Book page" in the admin menu, and I see tabs to create and edit drafts when viewing a book page.

My "book author" role does not see any of this though, despite seeing controls for 3 other content types just fine. The node permissions allow book authors to "Create new content" for the book page type. The 3 other content types also have "Create new content" and no edit permissions, and they all work fine.

For the 3 working content types, if I remove the "Create new content" permission, the admin options disappear from the menu and tabs aren't shown, and the menu and tabs reappear as soon as I recheck "Create new content". So it's just this Book module content type that's giving me problems.

This is a Drupal 7 site, with a few contributed modules that affect content access, such as Workbench Moderation and Organic Groups. I have also tested out some other content access modules in the past, such as Workbench Access and Domain Access. All these modules have long been disabled, however, and I have rebuilt permissions several times since. I suppose it should be noted though that I only just recently enabled the Book module, while the 3 working content types were all in use when I was experimenting with Domain Access, Workbench Access, et al, so maybe there are some lingering settings in the database?
I'm not quite sure why this started working, but all went right with the world when I added the "Book page: Edit own content" and "Book page: Edit any content" permissions for the "book author" role. 

Two odd things with this though:


I'm sure I tried this at least once before earlier today
I immediately disabled both permissions again to see what would happen, and nothing did, i.e. the book author role is still able to create and edit draft Book page content... which is good, but weird