Do you have power to the inverter outlets when connected to shore power or with the generator? If not I would check your GFCI. Then, you could have a bad transfer switch in the inverter.
If it only happens on battery power try CountryFit's recommendation but also check your GFCI.
Pete - Full Timing
2000 Country Coach Magna 40' Indulgence, CAT C10, #5892
2019 Ford Ranger XLT