Just thought I’d revisit this, as I’m not sure if it has been pointed out yet… but what are your audio connections here? Where is the cable from SYNC OUT on the volca going, and what is going into the A/B inputs on the OT?
Your audio cable should be plugged into the headphone out of the volca, and into the A/B inputs of the OT to make/sample sound. Otherwise, if you’ve got SYNC OUT going into A/B, you’ll record sync pulses only.
Apologies if you fixed this after taking the photos, but it seems like something worth trying.