I replied in another forum.
First, IN the RV, turn off ALL circuit breakers, INCLUDING the main.
Second you need to plug in two items to that GFCI, either via a multi tap extension cord or .. Well it is a duplex receptical.
one "Trouble Lamp" also known as a "Drop Cord".
Turn the lamp on and then plug in the RV, if the lamp holds GOOD.
(I will comment here if it does not, Forgot that on the other forum)
Now bring the lamp into the RV.
Turn on the breakers, Starting with the MAIN, one at a time. So long as the lamnp stays lit, count to 3 and turn on the next breaker, When the lamp goes out.. Note the breaker you turned on, Turn it back off, Reset the GFCI and continue till you have turned on ALL the breakers and hopefully just one is off.
Now. how is that breaker labeled and what is NOT working in the RV. (You may need to use the light to check outlets and such)
Suspect list:
COnverter or Inverter
Fridge
Water heater
These are the big suspects.. Generator bonding may or may not be an issue but it should not be due to isolation via thetransfer switch.
Now, if the light goes out when all the breakers are off..
Suspects include an INVERTER if you have one (Bonded imnproperly) and shorts in the wiring.