for about a month or so now my iPad Air is doing something very annoying. When I go to use the four finger gesture to close to the home screen it doesn't work. Now if I rotate the iPad from horizontal by 180 degrees and back again the gesture function works until the next time I shut it down using the cover to close. It's a major pain, if I reboot it ( hold down power and home) it works until the next time I shut it off. I look kind of funny rotating the iPad a 180 degrees and then using the gestures to close to home screen. Any advise or help appreciated. Almost forgot, I'm using version 8.1.2.