it powers some outlets ? but not all ?
that is normal, the outlets NOT powered, could also have your power charge converter on that ciruit
if that was powered you would be in an endless power 'DRAIN LOOP'
you can't use battery power to charge batteries
even RV's that come from the factory with 'all outlets' on inverter
have items like the charge converter, a/c, etc.. not thru the inverter
addon install like you have almost always have only 'some' circuits powered
usually TV, bedroom, bathroom , depending on where the converter is mounted and how it is wired, maybe a kitchen outlet