Hey, first of all, love the mod!

We're running it with a bunch of other mods (https://www.curseforge.com/minecraft/modpacks/soup-smp-collection) on our server and just ran into the issue that the books can't be placed into the smithing table when they are already Upgrade: 1. Upgrading them to Diamond level works just fine.
Granted, the issue might very much be with a different mod because it's by far not the first bug, but I wanted to shoot my shot here first.