Fbm Fractal and animated phase = no render

[mitchgates]

Using AB 4.0a here under Max 2008 32bit. When using Fbm Fractal noise with the Phase low and high set to unequal values the effect renders blank (black rgb, no alpha). This only seems to happen with Fbm fractal noise, and affects raymarcher and octane shaders. Even if you disable the AFC curve it won't render if the two numbers are different. For example if Low is 0.0 and High is 0.1 it won't render. If they are both 0.0 OR 0.1 it renders fine. If Low is 1.0 and High is 0.9 it won't....see the pattern?

Thanks,
Mitch