Vanilla bookshelves use a property called "enchanting power" that is part of the block and set to 1. This mod reads the enchanting power of all surrounding blocks and adds them up to calculate the amount for the bookshelves requirement.
Apotheosis does not use this mechanic and did not set this property for their bookshelves.
I need to find a fix for this. Maybe a tag for blocks where if it does not have this property but is tagged it will default to enchanting power of 1 (= vanilla bookshelf).

Mojang has introduced a new tag for this in a recent snapshot for 1.20