• OG installed
  • all nodes have an audience (group) assigned
  • some of my book pages show the book breadcrumbs as expected
  • some book pages show the breadcrumb for: groups -> groupname

This was an ugly UI bug on my site. The breadcrumbs seemed random, and when viewing a book page that showed the OG breadcrumb, there wasn't any obvious link back to the top book node (at least, not anywhere near the top of the page like it should be).

I see that node.module node_invoke_nodeapi() loops through module_implements(), and calls the *_nodeapi() for each implementation.

I guess that if book.module is called first, then og.module ends up overwriting its breadcrumb when og_nodeapi() calls menu_set_location().

As a workaround, I've commented out the call to menu_set_location() in og_nodeapi(). I don't have any suggestions for a proper fix.