I read this question, but it's not the same as mine: Why is Harry Kim senior staff?
ST Voyager "Nightingale":
JANEWAY: You've been in command on Voyager before.
KIM: On the night shift, for a few hours. It's not the same thing. You and Chakotay are always a couple of decks away, ready to take over if anything goes wrong. I've been on Voyager for almost seven years and I'm still an Ensign.
JANEWAY: If this is your way of bucking for a promotion
KIM: No, no, I understand there's a command structure and that our circumstances are unique. But the fact is, if we were back home, I'd be a Lieutenant by now. Maybe even a Lieutenant Commander.
During that same time Tom Paris went from a criminal prison, to Lieutenant, demoted back to Ensign, and then re-promoted back to Lieutenant.
Harry only had one (minor, fell in love w/an alien) mark against him in seven years and played a major role on the ship including being included in senior staff meetings and Operations Manager.
I realize Harry states in the quote above that their "circumstances are unique," to give the Captain an out in the conversation, but this is not an answer. Tom Paris was promoted in rank during those same circumstances and did not have the training/grades that Kim had, and had major marks against him including demotion and being thrown in the brig.
Why by this point wasn't Harry Kim promoted?