Fen

Ok. I searched on google to find a fix but I couldn't find anything directly relating to the issue. Maybe my search terms weren't exact. Is it a quest or a certain book that causes the issue?

As with the title; I noticed around the time I got to the Dark Cuboard, after I stole a spellbook and opened it, only 2 spells were listed in the 5th category. I then checked my other grimoires and the same had been occuring. I restarted and reloaded but the problem still existed. Aby ideas?