Player is unable to put plants (saplings, flowers, ferns) into flower pots

I was in a superflat world with the preset 3;64*minecraft:iron_block;127; and I attempted in both creative and survival to place a sapling fern and pink tulip into flower pots.

What I expected to happen was the flower pot to change data and display the plant.

What actually happened was that the flower pot remained empty.

How to reproduce:
1. Place flower pot.
2. Attempt to add plant.