Player repeatedly moves up and down when holding the sneak and jump buttons while inside scaffolding

Summary:
When inside scaffolding and holding the sneak and jump buttons at the same time, the player repeatedly moves up and down the scaffolding instead of staying in place.

Steps to Reproduce:

1. Create a pillar of scaffolding
2. Stand inside the scaffolding
3. Hold the sneak and jump buttons at the same time

Observed Results:
The player repeatedly moves up and down the scaffolding.

Expected Results:
The player stays in place, like when holding the sneak and jump buttons while flying in Creative mode.

Video:
Camera.mp4