The issue occurs when the device's orientation is changed, a grey block appears at the top left hand side. I have used XCode's simulator and environment inspector tool to try find out whats with the grey block, with no luck it just doesn't want to be inspected. I have tested a few devices iPhone 6 and 7+ aswell as iPad mini 4 and it still appears on the device.
https://i.stack.imgur.com/WVxJn.png