scaffolding doesn't negate fall damage when newly placed

Scaffolding should normally negate fall damage when you land on it, even when it is one block thick. however, if you place it right when you land on it, it doesn’t negate or reduce the damage.

how to reproduce: fall from a relatively short distance and place scaffolding right when you land, so that you are standing on it and not in it.

expected result: fall damage is negated.

actual result: you take fall damage.