Whilst playing Normal SSP [Snapshot 18w47b], I noticed that nearby mobs and dropped player items turn invisible upon death. No shadows present. Items can be picked up as normal. Mobs make noises and attack as normal.
I thought this was an issue with dying near a spawn area, but it may be more related to the death site itself.
Initially, logging out of the game and logging back in can restore visibility, at the risk of the said mobs swarming you as you log in.
Continuing to play after death revealed the invisibility issue occurred closer to the site of death. Multiple deaths restored the visibility of some mobs while other mobs closer to the death site became invisible.
Possibly related; whilst playing on the same session and world, I dove down to a shipwreck. While opening a chest, it looked empty. I closed it and opened it again. The entities inside appeared as normal.
Gave this a thorough test in a new world.
Spawned in a spruce forest with sheep, a bonus chest, and a lava pit nearby.
Jumped in the pit, the sheep and items inside the chest remained after respawning.
Flipped to Creative real quick [oddly, the music changed to a new track as I did so] and grabbed zombie villager eggs and spawned half a dozen before flipping back to Survival.
Death by zombie villager; all mobs and items in the chest remained.
Death by jumping into the pit after being chased by zombie villagers; same result.
Unintentional death by being knocked into the pit by zombie villagers; entities still remain.
Death by zombie villager for good measure; entities still remain.
I think it's safe to say this has finally been fixed!