i don’t own an octatrack and i don’t know how it works, but i think on the hermod you just need to set the “input mod” value to the corresponding cc in the midi fx(the one you find in the first slot of the midi fx page). of course you can only have 1 cc mod per track. then route the cv out of that track to the filter cutoff. something similar to this if i’m not misunderastanding what you are trying to do (sending a cv out controlled by a midi cc)