The Shulker teleports to an invalid block and stays there and I reproduced this in a creative world for the videos & screenshots. When moving Shulkers in Survival for a Shulker farm, every Shulker I transported in a minecart always teleported down into the railing. If it wasn't the railing, they would teleport onto a Piston that had a Button on it or into Pressure Plates.

Intended Action: The Shulker teleports to an open solid block.

Blocks/Items affected: Buttons, Rails, Pressure Plates