UR22: When I turn the knob towards "input", there's no sound

I’m using Logic and a UR22 interface. In the past I remember there being a sound, like the raw sound of my voice coming through without any vocal processing. Now there’s just nothing when I turn the knob towards ‘input’ away from ‘DAW’.

Is something connected to the inputs? How and where?
Is any gain applied to the input signal?