you cant go downwards in scaffolding blocks that are not connected directly to the ground. this may be because of my switched keybinds, but it works sucessfully when I crouch in scaffolding that are connected directly to the ground. I can go upwards in both those which is connected to the ground and those which are not. In the picture down below you can get a better Idea of what i try to describe.

This is a bug on Bedrock edition aswell, and now it is on Minecraft java edition as well.
I may create a video if needed to confirm or to show and describe better

relates to MCPE-38063

How to reproduce?

Make the scaffolding structure as seen in the picture below
then try to go downwards in both the towers.
the one on the left should work (the one connected to the ground) and the one on the right will not work. (the one not connected to the ground)

to go upwards press space and downwards press shift (crouch)