Mobs will spawn while playing for about 5-10 minutes, then spawn very rarely. Easy level may go several game days without a mob. Switched to Normal, got three zombies total in a night, nothing else. Went running through mountains and mesas looking for mobs to kill, nothing.

Started with the most recent update.

If I exit the world, then return to it (not exiting game), the regular spawn rate will return for a few minutes.

Sure, it makes it easy to mine all kinds of swag, but it also slows XP and nerfs the game toward boredom.