Does Thor use wiring codes?
Get a screwdriver and pull it out the wall, get the wiring code and look it up on your coaches wiring diagram. It will tell you where it goes.
A long shot for fun, I remember looking at 2019 Windsports; and if memory serves me I saw a toggle switch in bath that didn't seem to control anything either.
Somehow it seems like I was told it control some light outside?
Not the RV door patio light but some other light? I just can't remember but the thought may spur someone to confirm or get what I am missing