References: Fibered Knots
The 13 12-crossing knots for which the Alexander polynomial is monic and has degree twice the genus of the knot, but which are not fibered are the nonalternating knots, 12n_x, where x = {57, 210, 214, 258, 279, 382, 394, 464, 483, 535, 650, 801, 815}. Four of these were found by Mikami Hirasawa and the rest by Stefan Friedl and Taehee Kim.