Yep, unusable as it stands right now. I had a half dozen books from mods such as tinker's construct, environmental tech and some others. Put in a chest, picked it up carried it around for a few minutes, set it down set down another, newly created and empty chest next to it (which might have been what caused the issue). When I opened the combined chest I saw two generic minecraft books in it.

Update with the fix is now online!

https://minecraft.curseforge.com/projects/betterchesting/files/2722015