Hoglins naturally spawning on slabs. being immobile

What I expected..
Hoglins spawn on a non-slab block ,and chasing after you.

What actually happened..
Hoglins spawn on the slab, being immobile

This naturally occurs when you load a bastion, i'm not sure about reproducing the bug, but it naturally occurs when loading a chunk near a bastion.

Reproduce:

1. Enter Nether

2. Load a Bastion

3. Locate Hoglins spawning on slabs

I feel this ruins the challenge or purpose when encountering this structure, it would be better if they could spawn on a non-slab block.