could do with VCE and two layers of brick plates
top brick: on player touch check if player is crouching
if crouching decollision both plates (allows playres to fall through platforms)
bottom brick: on player touch decollision plates + add velocity up
obviously a hacky unreliable method though. I don't see how you can make things only collide in one direction code wise though.
I think it should be possible in some way, as each face of the brick collides in one direction (you can go out of bricks, but not into them)
there's a difference though since you're starting outside the brick. its like teleporting into the middle of a vehicle - it doesn't trigger collision checks because it checks the bounds of the brick.
maybe if the brick had a custom (collision) .dts......