20w16a Hardcore mode bugs: No hostile mobs!

Me and a friend are trying to play a hardcore mode world in the newest snapshot but here are no hostile mobs spawning at night. We're on a server she owns! 
The issue is the same on a single player world, no hostile mobs. 

Everything else in the world seems to be unaffected. We haven't tried to use a mob spawner so I'm not sure if mobs can spawn in this snapshot on hardcore.