Jesse, it can be as simple as a wire nut coming loose which then causes the wire to not make good contact.
After traveling for a day I found my 12 volts lights
weren't working and they had been prior to leaving home. Converter, fuses etc. were all OK. So we started looking at the light
connections. Sure enough one of the connections in the kitchen overhead cabinet wasn't making good contact. As soon as we reconnected it...viola' lights
There was a connection at both ends of the kitchen cabinet, plus the porch light
is on that line.