I’m able to reliably reproduce this on a modded Shruthi 4PM with CV inputs for cutoff/res/vca with firmware 1.01. This is with no MIDI connections:
Turn on Shruthi which goes to default init patch, go to Filter page, turn Cutoff to 0, play note (i.e. send CV envelopes to cutoff/vca with ext. audio to input), go to mod matrix route LFO1> cutoff in slot 1, turn amount to 63 and there is no modulation. I can do all the above and set cutoff to 1 instead, and it (LFO1>cutoff) works. When the problem happens, if I manually open the gate (hold encoder) the modulation kicks in and stays on even when I turn it off. Using the default LFO2>Cutoff routing on the Filter page is not affected.
Just curious if this was by design? Otherwise, using the unit in ‘full analog’/no MIDI with CV and modular VCOs is awesome. The input overdrives so wonderfully.