@davemand: Can you give me an example of the name of a book that is getting the single letter shelf? And what is the save template you are using? Is it what you posted earlier, or something else?
What you are describing shouldn't happen. The shelves should be created when the book is first sent. Even if for some reason the book isn't processed by the device and shown in the library, the shelf should still be there but without anything in it.