Online reset bug

So i did some testing and well...It's some kind of an online bug (NOT Lan)
What happened was:

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Join friend world                            (OK part)
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-press "win"                                   I  (<-Here's how it starts)

-press other app.                           I  

-come back to game                     I

-game reseted                               J  (<-Video 1. )

-join friend world (again)

-game won't let me join back

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Aftermath

-reseted Minecraft / Computer

-join friend world (again X2)

-game won't let me join back

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