Just a gentle reminder - GFCIs trip because of a leakage between the hot and a ground, or a leakage between the neutral & ground, (or rarely, between a hot & another circuit's neutral) not from overloads. The circuit breaker protecting the wiring is what will trip on an overload. GFCIs require power to reset, i.e. if both are tripped, you must first reset the circuit breaker, then reset the GFCI.
As to why the particular breaker tripped, when 2 or more breakers are in series (as in an Escape with an inverter & transfer switch) either one may trip. I've had cases where a 500 amp breaker and 200 amp breaker were in series feeding a theatre dimmer board. The 500 amp breaker was closer to the main distribution panel, however it tripped rather than the 200.