It works exactly the same now in bg3. If your character stays next to the ladder it will block the passage. Experienced it in a fight with Polma and Gut yesterday.
Oh great!
a.) Were you at the top or the bottom of the ladder? I wonder if there's a difference...
b.) Given BG3's instant-ladder-movement, does standing at one end of the ladder block characters from getting on from the other end? I presume not...
