I've been experiencing the same thing here but in my case, using a "Switch easy" case on iPhone 5. The raised part of the case, covering the home button prevents your finger or thumb from being able to swipe from the very bottom of the screen (although swiping from the top accesses notifications without a hitch). With the case removed control centre works first time every time; case on and I get about 5% success rate, even trying from the extreme corners. Not very useful for such a potentially useful feature. 🙁 However, I'm glad it's just the case which is the issue and not the phone itself. 🙂 Time to look for a new case, I suppose. Shame as I really like the soft, protective silicon of the "Switcheasy".