I was playing in my redstone test world to see if I could manually despawn mobs, however when I switched it from Hard to peaceful and back again no mobs spawned again. My test world is flat, set to hard mode, and is at night. This means that mobs can't be spawning in caves or anything. I checked all my structures to see if any spawned in there, but none did. I don't understand how the mobs completely stopped spawning after I switched it, nor do I know if there was a lot of mobs before that. All I know is that I flew around for about 15 minutes at night, set to hard, in a flat world, with no mobs to be seen. If I were to do this on xbox one edition, mobs would instantly spawn. Please, fix all the spawning issues in this game. It's making it thoroughly un-enjoyable and frustrating.