While enchanting a book with a level 30 enchantment the experience was used but no the outcome was just a regular book.

I have a good understanding of how enchanting mechanics work and how occasionally the item doesn't enchant if a item fall outside a certain range when working out the enchantment it will have yet this usually refunds the levels used, however when enchanting a book that falls outside this range it does not refund the levels and causing the player to lose out.