Spellbook bugged for NPC

The NPC Caspian Thorneveil in my party was generated with a preconfigured spellbook. The number of of prepared spells does not match what is listed. The spell books shows 8/8 spells prepared but he only knows two spells. I tried to correct this myself by clearing out all the spells he knew but this did not work. I tried having Franz clear out the book as well, but that did not work either.