Such as other apps from Windows store like Office 365, Facebook, Messenger, Instagram that have issues when are minimized for long periods and get a black screen flashing when moving the cursor, but unlike those, Minecraft, when minimized, now gets a solid white screen that unable every display action and only the background music is what remains. Can't tell if anything happens whether the main menu or in-game course. The only way out is to close the window. You can't pause for long time, do "be right back", or leave Minecraft a while to check other things (for example explore some info in Minecraft Wiki and then get back to the game).