Screen goes blank after 20-60 seconds in game

well after about 20-60 seconds of messing around, the screen goes blank. all the touch GUI is there but everything in the world beomes invisible, no pause menu, im stuck like this until i get out of the game completely.
completely gamebreaking/unplayable bug

acer iconia one 8 b1-810
android 4.4.4 kitkat
no mods/addons
no textures
just vanilla mcpe!
i have tried everything but nothing seems to work except complete reset.