The item seems to be classified as an "Arcanist's Grimoire" according to this tooltip: https://na.finalfantasyxiv.com/lodes...m/c10d086f191/

Meaning that the game probably will not allow you to glamour it into a Scholar's Codex, even though it is equippable by both jobs at the appropriate level. Dumb, I know, but that's probably the issue you're encountering. Good way to test would be to attempt to glamour a level 60 SMN book to see if it works. If it works for the SMN book, but not the SCH, then you know the classification is preventing the glamouring.