Welcome to the forum
Since your bathroom lights are 12V, the breakers are not in the equation. If all the other lights work then we need to focus on those lights. Can you post a pic so we can figure out how to get them apart?
First thing is to remove the switch, make sure you have 12V going into and out of the switch.
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2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.