Very few sounds and can’t see mobs

When I open my world I can hear very little noises, I thought at first I was set to mute. I hear some music occasionally and occasional sound when I do certain actions. For instance I can hear levers but not pistons. I have been working on a cave project so my game save has been there and I didn’t notice at first but most mobs appear to be invisible. I can see shadows or effects (for instance the little puffs when a slime jumps and lands) but not the mobs themselves. I have experienced invisible creepers , zombies, slimes, and chickens so far. The latter when I ventured to my campsite  where I had set up a home away from my base while I work. But I emerged at night and didn’t want to venture home to check my farm mobs. Not knowing how I could avoid any invisible hostile mobs that don’t die in sunlight like  creepers.