Troubleshooting _rotary_

I assembled two rotary kits last week with a friend, and one worked perfectly but the other isn’t registering the selected effect. It transitions between the two sources and is audio reactive, but it just hard cuts back and forth instead of transitioning smoothly no matter what effect is selected. Tried it both in a V4ex and regular V4. I am pretty new to soldering and wonder if I damaged a component in the process? I checked with the instructions several times and everything is in the right place, all directional components are oriented correctly. My friend also went back through and went over all my solder points to clean them up and that didn’t help. Any advice on where I should direct my attention for troubleshooting? Is there a specific component that would lead to this issue? Thanks!

interesting - its not immediately obvious what the issue would be here. it would be helpful if you posted a video from the same mixer comparing the working unit and non-working unit…