The Rank setting only applies when a group uses Uniques for diversity. With Portfolio, the diversifier decides what goes in and the rank order doesn't drive it.
Thus, our default recommendation is to simply use Portfolio diversity, because it’s a stronger overall approach to selecting lineups.
That said, if you prefer to use Min Uniques, you’re probably best served using either Target Contest → ROI if you’re on Ultimate, or Saber School if you’re on Starter. This will use the contest sim data to rank and select lineups.