Welcome to iRV2.
I'll have to ask a couple of questions.
You say when on shore power the inverter doesn't work .
Do you mean the inverter ( which is actually a inverter/converter/charger ) isn't charging the coach batteries ?
Or do you mean the outlets that are normally powered from the inverter don't work ?
The breaker that trips , is it on the inverter , or is it the breaker on the shore power supply ?
Most of what you describe , can be due to internal issues with the inverter.
Can you add any information, you have ; on your inverters brand and model; to this post so we can provide more information on testing it.