Smol bug: Wig-wag lights on D-series not working

As the title suggests, the wig-wag lights dont function on the D-series pickup truck. There is an option for it in vehicle config, but it doesn't seem to do anything. For comparison, it does work on the Grand Marshal.

EDIT: the front lights dont seem to do the Wig wag, but the tiny ones on the sides of the truck do be doing flashing. Not sure if the headlight units should also be flashing.