Bubble columns are not removed upon end portal creation

Steps to reproduce:

1. Create an end portal, but don't fill it with eyes of ender fully.
2. Place any solid blocks on top of the end portal blocks.
3. Place soul sand on the ground, one block bellow the end portal blocks.
4. Fill the resulting "box" with water.

Expected results:
Bubble column blocks, above the end portal blocks, should be fully destroyed upon end portal creation.

Observed result:
Bubble column blocks are only destroyed where the end portal blocks are placed upon end portal creation.