Fleether Keys

i killed myself in the overworld and the same thing happened. you can also kill the decoy of yourself, but that doesnt free you.

I experienced this same issue when i died in the nether, not due to /kill. after i died i died a 2nd time in the overworld for no reason. i could fly around in creative, but it was like i wasn't connected to a server (chunks would load, couldn't enter nether.) when i relogged, i died instantly then had the same issue you are having.