I made a command block system that summoned a Zombie at the location of your death, but I ran into a problem when doing so. On the re-spawn screen you could see it there, but once you hit Respawn it disappeared, and yet you could still still hear it running around and burning in the sun. I thought it odd, so I tried again with an ArmorStand with the same results. Later I got my brother on a LAN server and tried again, and this time he could see it, while I couldn't.

----Summary
Expected results: The Entity summoned would be visible to all players.

Actual results: The Entity summoned is visible to every player except for the one that died to summon it.

How to Reproduce:
1: Create a scoreboard objective(mine is called health) to track a players health
2: Create a dummy objective (mine is called dead) that gets flipped once you die so you only summon one of the Entity.
3: Have a repeating command block chain running the command "execute @a[score_health=0,score_dead=0] ~ ~ ~ /summon ArmorStand ~ ~ ~" followed by the command "scoreboard players set @a[score_health=0] dead 1"
4: Kill yourself (make sure you set dead to 0)
5: Stare at the empty space where the ArmorStand should be

Other Info
1: After some more fiddling around it appears that this doesn't always happen, so you might have to try a few times to get it to work... darned bugs being inconsistent.
2: Re-loading the world will make the Entity visible to all players again.
3: If you use this with an Enderman teleporting will make it visible again.