Hello,
Trying to shift elevation by dropping down a 1 block gap whilst sneaking/crouching does not work. This behaviour makes very little sense, and does not appear to be present in any option to turn it off. There appears to be very little documentation on the cause of this, so I'm hoping someone here knows more. It is incredibly annoying.
Event that brought behaviour to light: Attempted to follow deer down a shallow hill whilst testing viability of hunting. Could not follow it with the crouch button pressed.