Just sharing my experience, not bashing. I actually really like my WW. I've never seen a wiring diagram and I bought the 2006 model new in 2005.
On mine I had an issue where the installers (I may use the word idiot later because it's shorter) wired using the layout for a regular FS. My trailer is an FSC, so the refer is on the door side with the 12v access panel underneath, then as you go forward it's the water heater, then the furnace, then the water pump (inside access only) and then the under bed storage.
I found that all the wiring was originally terminated over the water heater by the idiots and then spliced using crimp style connectors and run to the 12v panel. Over time I have had to fix both the refer (direct run now) and the feed to the stove hood controls (Water pump, water heater...). They were pinched inside the wall between the heater and the extensions to the 12v panel. It's not easy but it can all be accessed by removing internal and external covers.
I suspect in your case you have a loose connection somewhere, unfortunately you will have to follow the lines. I would start with the switch, they probably use a single feed from the fuse block to feed all the switches at the door so if you have problems with multiple lights that's most likely it.
Good luck finding the gremlins, I bought a 12v test light just for the trailer and rigged a 20 foot cable with alligator clips for the ground so I can use it anywhere to test 12v.