That switch operates mine on the 171rbxl (your little sister/brother).
Turns out the wire connections came loose.
Look under your trailer where the LED light strip wires enter the cloth membrane.
There is a crimp wire connection here that comes loose. Recrimp the wires and hopefully this solves the problem.
And yes mine worked at the PDI - but came loose before the first overnight stop home.
2019 Wildwood Xlite 171rbxl
2018 JGC Limited 4x4 w/tow