Since I went to get the 0.12.1 Beta 3, it could have more bugs, I started seeing weird things on MCPE since I installed MCPE 0.12.1 Beta 3. On the game, I clicked on the overflow button(...) to change blocks on the slot selected, and when I click on another slot of the hotbar, it puts the block in, and changes the block to a grass block or any other block that is highlighted on the + sign on the center of the screen.
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This issue was reported previously as MCPE-9545. Comment your experience there!