Hi team
I experienced this when first building my Helix system, and an afternoon with a multimeter, cable ends and a soldering iron had me sorted.
I do see this pop up from time to time, and figured I would document my findings/actions for others to understand what's going on when this 0-100-0 sweep happens.
Walkthrough doc with photos attached.
It might not be 100% correct, but it's what worked for me :)
Helix EXP TRS-TS Cable.pdf