lol, I've suffered in silence with similar. It's frustrating.
Our right turn, LED, will come on and stay on. Sometimes. For weeks on end I found out. I've checked, traced and back tracked, nada. Wiring isn't foreign to by by any means. I have 20-25 trailers any given date, and up keep and diagnosis is constant.
I usually start with the obvious and most likely culprits, the plug ins. They get the most 'action'; even one little strand on a wire crossing can pick up enough current to keep an LED on. Problem with campers, trailers, etc, they are not very good at maintaining color coding (brn tail, green right, yellow left, etc) and the wires disappear into areas not readily accessible. All this leads to a hard to trouble shoot problem and often, hard to fix/work around.
My light doesn't come on currently, so I don't worry about it this month.
Let us know what you find.