Aaaand ok, bigger problem. The data cable is wired in a straight line, but the PCB assumes pin 1 on one side maps to pin of the other (not inverted, as it's wired).
Let's see if there's any way I can re-arrange the contacts in the cable as a temporary fix.
Mid term I'll spin a tiny adapter board that mirrors the pinout, and of course on the next board design I'll get it right.