You said Converter, on most RV's the converter is working any time you are plugged into shore power so how did you test it when it was not running?
Now.. on some RV's there is a device called an INVERTER, this is optional.. I have one.. An inverter may be wired two different ways, Ground bonded to neutral, or unbonded. It matters not..
On the MAINS power. it is bonded, so an inverter with power pass through switches all 3 leads. Hot, Neutral and Ground. thus when it's "Not Running" neutral and ground are bonded and a ground fault is possible.
If the inverter is hooked up so that the ground is NOT bonded. then when you trip the breaker that feeds the inverter and let it power the down-line devices, one of which is often said GFCI, it is not possible to generate a ground fault, for there is no ground to fault to.
