Clifford, Thanks! Brian, Good to know maybe I don't have a problem with the neutral-ground bond. However, during my testing - read more below, if I throw one of my main panel breakers ON, the GFI immediately blows. If I leave all of them Off, it works for 5 - 10 minutes and then blows.
I have disconnected the green ground wire in the Trace and left it disconnected. The shore cord is a 50' 30amp 10 ga. It is not curled up - I always stretch it out and then bring it up to the bus. However, I have a 15/30 adapter at one end and a 30/50 adapter at the other. This 15 a circuit is in an outbuilding that is quite a long distance from the house panel and it has a household refrigerator on it that I cannot disconnect. In consideration of that possibility, I set my inverter to Charge only (no invert) and the charge amps to 5A. During my testing, I had all breakers in the bus Off so that only the inverter/charger was pulling a load. I have a power conditioner that indicates 117 volts AC, 5A AC and 60 hz after throwing the breaker in the bus. Those values hold steady until the gfi blows.