Creepers are not pulled down by magma block bubbles in one-high water

Creepers are not pulled down by Magma Blocks consistently in 1 high bubble water whereas other mobs are. They seem to have to bop up to a certain height and fall back down again before they are then pulled down.

Steps to Reproduce:

1. Build a 1x2x1 hole
2. Place a magma block beneath the hole
3. Put a water source on the bottom half of the 2 tall hole
4. Spawn a creeper above the water

Expected: The creeper sinks from the created bubble column.
Observed: The creeper does not sink, but instead bobs up and down at the top of the water.