Whenever I choose Save Book from the Bookfile panel menu a dialog opens and prompts me to save a new copy. I expect it to simply save the Bookfile quietly, just like any other document.
This has been happening with versions as far back as I can remember, and I'm currently on the latest version of InDesign CC.
It's not a big problem, but a bit of a nuisance each time I want to save.
Mac OS or Windows?
Seems to me like file permissions problem.
Thanks Doc, and apologies for tardy reply. I've checked the file permissions and all seems to be right. I've also re-made the bookfile with the same result.