This is most noticeable when switching between Filter/Noise in the Sweep FX section of effects, but it’s prevalent in other areas when using the FX Banks 1 and 2. The loudest pops happen with the Sweep FX buttons, and they’re being recorded in my output WAVs.
Any idea what’s happening? grounding issue? it’s really loud and super jarring, and very difficult to edit out later.
Are the pops audible over the master output, headphones and zone outputs or only audible on the recording?
Pretty easy to reproduce - Start playing a track, turn the filter sweep knob just slightly past 12 o clock and then go back and forth between the Filter / Noise effects. It’s audible in the master outs and headphones as well.
So you change the Sweep FX while they’re listening (i.e. with the knob not in the 12 o’clock position)? 
No, but in this case the knob happened to be the tiniest hairwidth past 12 oclock. And i can think of a few practical uses for changing effects with the knob active, totally depends on the moment.