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It's unclear if you have any bias on those controls - if they are at the zero (middle) position the modulation matrix will not work on them. However if they're slightly turned in the direction of the wanted modulation, without actually engaging it, then it will work. This is because the audio mod knobs that have two modulation options are switches as well as one of two different variable parameters, either the left side parameter or the right side parameter. When not at the zero point it engages one of two selected modulation path, e.g. for VCO1<VCO3>VCO2 the left side makes the connection VCO3 > VCO 1 and the right side makes the connection VCO3 > VCO 2, and you can adjust that one modulation path with the knob.
So to enable these parameters to be modulated, there is a small dead band around the 0 position in which the switch for the mod path is engaged, but the actual modulation is not engaged until you turn the knob a little further. To use the matrix to modulate these parameters from zero, you need to have the knob just to the side
of the middle marker. If you audition a VCO while making this adjustment you'll hear a slight momentary change in pitch just as the modulation path is switched in.
The VCO 1 > VCO 2 knob works as any normal knob since it's a single parameter and therefore no switching function is needed.
From section 4.2 in the user manual:
"For the bi-polar knobs to be used in the modulation matrix, you will need to turn the knob in the direction that you want it to modulate when assigning it. There is a small dead zone on either side of the center detent that will allow you to have no modulation but still allow the knob position to be sensed."
