Gates+Pinion freehub clicking?

Hello! I have a Gates Carbon Drive set up with a pinion gearbox, running on a Bontrager rapid drive 108 rear hub (Shimano HG freehub body). On pedaling and rolling the bike backwards, im getting a very loud fast clicking, which sounds like it's coming from the rear hub. Using the Gates OEM freehub spacers, with as straight a beltline as I can eyeball.

My current leading ideas are the spacer stack shifting, the splined rear cog shifting, the beltline being slightly misaligned, or my freehub body being broken for some reason.

This drivetrain only has a few hundred miles on it tops (mainly due to cockpit ergonomics I'm ironing out), so I'm doubtful anything is truly broken.

The noise does not occur while freewheeling, only when the belt is moving.

Any ideas or advice would be appreciated!