Well it means that you have a really weird problem that most likely can’t be solved on this forum. I can’t believe it is somehow related to a defective charger/converter. To prove that your charger/converter is working properly do this test. Measure your battery voltage without generator or shoreline power. I think you said it was 12.4 vdc. Then on shore line or generator power, the battery voltage should increase to at least 13.8 vdc indicating that your batteries are being charged. If no change then your charger/converter is defective or AC power to it disconnected or associated circuit breaker tripped?
Also most motorhomes are equipped with a house battery master ON/OFF switch. Make sure that switch is ON.
