In the past, Structure Void had a hitbox and we could place signs, frames, stairs and blocks on it. it was the same as the barrier block, but allowing entities to pass through it. But currently, this is not working, the Structure Void block is just preventing the passage of water and lava and letting the player pass through it, we can no longer place plates, frames and blocks on it, as it no longer has a hitbox.

Note: it only has one hitbox, when we have the Structure Void block in hand.