Mobs spawning in the air in custom Nether biome

In one of my custom biomes in Nether Update Expanded, for whatever reason, some mobs spawn 20+ blocks in the air or above lava and repeatedly fall to their deaths. This mainly seems to happen with Zoglins and Hoglins. Is there a known way to prevent this from happening? I have found two people having similar issues (but with cave biomes) from 2023 and 2024, and neither of them ever received an answer.

Example of it happening

Biome generation settings

Biome mob spawn settings