This bug is still in the game as of 4/20/2013.  In my case, I had cast Anointed by Fire on Lord Relias in the Campaign game and while he had the enchantment he leveled and got Fire III.  At this point in the campaign, Relias was the only one who could cast the Anointed by Fire spell, so only one instance of the spell could be active at any one time.  However once he leveled to Fire III, the spell was no longer showing up on the Details screen for Relias nor on the Enchantments screen and thus couldn't be removed. Yet the spellbook was still indicating that it was active, as the spell was unable to be cast again.  So it seems like the spell was partially removed but not completely in the case of the spellbook.