Using Lightroom Classic CC ver 8.2 on iMac with 16 GB RAM onboard, operating system is latest version of Mac OS (Mojave). First, the book module does not work as smoothly as I was used to in some prior versions of Lightroom. Here's the problem: whenever I click on a new "picks" collection in the Library module and then go to the Book module to make a book, I find that the filmstrip also adds in all of the pictures I used in any prior book on which I was working. In fact, if I use auto layout, the module will fill many pages not only with my current collection but with the prior book collection. When I "clear book" everything empties out but the filmstrip continues to have all the unneeded/unwanted pictures in it. The only way to get rid of them is to manually select all of the unwanted old ones in the filmstrip and "delete from Collection." I have tried restarting Lightroom, rebooting the computer, resetting Lightroom preferences, and nothing seems to help. This seems like a bug. Or, is it something unique to my installation.