Streams Signal Bleed

CI’ve just bought Streams and I’m having a little problem, or is it normal?
I’m getting signal bleeding through when the Mod dial is between 7 and 3, at 3 to 5 it’s better, but not totally silent. I’ve tried calibrating it, which has made no difference. I’ve only been using it in Vactrol and Envelope modes so far. It does it on both channels.

Any suggestions?

Super basic question first - is Level Mod turned down and nothing plugged into Level input?

Yup, level mod is turned down with nothing plugged in apart and a vco into the in input and a line out to my mixer.