Fade During Snap FX

Hello. I have seen with 3 of the fixtures that I use, 2 of them, (cause one is a moving head spot with a color wheel only),when I don a snap color mix Effect, both eave and swing fix, there is still a fade shown. Even All 3 of them have this thing were the intensity snap and Sawtooth Fx Look Off, any way to fix this. Please and Thank You