All versions had this problem!

When playing Minecraft bedrock server, as long as you change everything to the background, when you switch to Minecraft again, Minecraft will automatically exit to the main interface. This problem also exists in win10 edition! 

Steps to reproduce:

1.Casually enter a server

2.After entering the server, switch to the background of the mobile phone

3.Return to this window of Minecraft

4.You are no longer in the server and exit to the main interface

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