When doing an advanced search, the last 6 months or so worth of sets and commander precons are not showing as selectable search criteria (Modern Horizons 3, Assassin's Creed, Duskmourn, Bloomburrow, Foundations, Marvel/Dr Who Secret Lairs, etc).

You can search up cards from some of those sets if you know the name or part of the name, but if you're trying to browse those sets for cards, you can't. Also, some of the Secret Lair exclusive cards aren't searchable at all.