Possible duplicate, but all others don't mention death in any way. Not sure if relevant.

Brand new world (Tested multiple times)
Start, don't go far from spawn, wait for night, get killed by a mob.
On death, mobs are still visible behind death message.
Respawn.
Move to where death occured
Mobs are invisible but can still harm.
Skeletons still shoot arrows (which they appear out of thin air) and zombies hunt and kill. Mobs can be heard and injured but are completely invisible.
Reloading world restores them until death occurs again.