Creepers do not run from cats on elevated platforms

The Bug

When Creepers are near cats, their programmed behavior is to run away if the cat is within 6 blocks of taxicab distance. However, they do not perform this action when elevated on a platform above the ground.

Steps to Reproduce

1. Summon a cat on an elevated 3x3 block platform and make it sit in the center of the platform.
2. Summon a creeper and observe that the creeper does not attempt to pathfind away from the cat.
3. Observe that even after the addition of trapdoors on the sides of the platform, the creeper ignores the cat.

Observed Result

The creeper didn't run away

Expected Result

The creeper would run away