Zombies again do not spawn in caves

Zombies are not spawning in caves (again). Reported this bug for a previous version and was fixed but seems to be back in the 1.16.57 beta.

 

I was testing despawning when I noticed no zombies were spawning when I created a roof above the spawning area.

 

Video proof: https://www.youtube.com/watch?v=jZ1ScJz74Qg