Creakings cannot spawn on a single layer of top snow

Steps to reproduce:

1. Load the attached world.
2. Wait for a creaking to spawn. If one has already spawned, type /kill @e.

Observed results:
The creaking will always spawn on the uncovered wood planks i.e the ones that don't have the layer of top snow. And on occasion will spawn on top of the pale oak block.

Expected results:
They should be able to spawn in a single layer of top snow, much like other neutral/hostile mobs.