[nellie27]

I had some success in connecting the NG3 to calibre, adding books, ejecting device via calibre, then ejecting via the icon in the taskbar-a very important step (you will be forced to delete all sideloaded content if you forget! and possibly reboot your nook!). I did not add books via a file manager.

I had created 2 (small)shelves, one with just sideloaded content, and another with sideloaded and BN content. Both shelves survived intact through this procedure.

There is room for more experimentation with this problem.