Item graphical glitch after locking and unlocking my phone while the game is running.

After update, I mess around my redstone world as usual, but every time I locked my phone while the game is running, all items what holding on my hand, so do items held by mobs, are turn into random color pixels, when I unlock my phone and continue the game. The glitch is not happen in older version of mcpe.
Some screenshots of the glitch are attached.