Volume pedal buzz/static in loop 5

[keg8605]

So I have my amps fx loop in loop 4 of the PBC and the volume pedal in loop 5. When all the way up there's no noise. When I lower it I get a buzz. Turning off the 2nd buffer stops the buzz but then the high end seems to roll off with the volume pedal a bit. Any ideas what might be causing this? Its a fractal volume pedal....

Thanks guys