I've notice this with my first wizard who is Storm school, but also when dueling in the arena with my opponents. It seems that whenever lightning strike is active, the spell following is nearly certain to fizzle. From the 20 or so castings I have seen in the last 2 weeks since I started, it seems as if the 10% boost is overwriting the base accuracy instead of adding to it.
Has anyone else seen this or is it just a really weird string of luck I have observed?: