I have a Victron Multiplus and everything on the inverter side works well. When on generator or grid there are no polarity issues. When on inverter alone I have the non inverted outlets showing reverse polarity Neural to Ground on the non inverted outlets is 1.5 v. N to G on inverted outlets is 75 mv.
At least one other user has the same issue according to my installer and he has checked the wiring throughout.