It's interesting how it's so commonplace to declare that because Janeway didn't promote Harry (or any other ensign save the one she "created"), he was an ensign forever. Realistically speaking, it's unlikely. Starfleet probably just reviewed all the ship's personnel's files, determined evaluations, time in service, the kind of work they did, commendations, reprimands, brig time (if any), and whether they were Voyager, Maquis, or Equinox. And, they doled out assignments and rank pips accordingly.
Most of the better ensigns probably achieved full lieutenant rank. The ones who struggled, or were former Maquis who retained their commissions, maybe had to settle for JG. Harry was probably one of the former. Given that his service was exemplary and he'd done LT-level work from the start, he might have made LCDR if not for the reprimand of his record.
Also, given that Janeway is the only captain who actually reprimands people for interspecies romance, maybe that was ignored as well.
