Put the summary of the bug you're having here

What I expected to happen was...:
I expected to see many spiders, zombies, skeletons, etc

What actually happened was...:
After 4 hours of game play, I've seen 1 creeper and 6 illagers. I've messed with my difficulty as well and that didn't fix it. I can walk around outside at night without seeing any hostile mobs

Steps to Reproduce:
1. I loaded my world
2. Flew around in creative to find a good starting place
3. Switched to survival
4. Waited for nightfall
5. No hostile creatures