1) Disconnect by changing a static ip or something of the sorts.
2) Reconnect, your body is still there.
Not sure if this is a bug, or if it's been reported (Couldn't find it) but yeah, this happened to me twice, each with the same disconnect error. Don't remember what it was though.
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I should have taken it in in F5 mode to have more proof, but the body disappears in like, 3 seconds.
Is it a modded server or a vanilla server?
Modded means like bukkit which has plugins and stuff(If you still don't know what is bukkit, just check if it has a ranks system and some stuff you can't do in normal Minecraft, if yes then it is a bukkit/modded server)
Completely vanilla, mojang distributed server. It was on a whitelisted server I play on.
Weird, since I know that happens on BungeeCord servers before... check if they have /server or /bungee, but I don't think BungeeCord is the issue, since I don't think that you are connected through a BungeeCord proxy.