Smartphone users Pixel and Nexus complaining about the December update devices to Android 8.1. According to statements on the support forum of Google and Reddit, the update brings trouble recognizing gestures.
It is reported that the device does not respond well to a swipe up, which should open menu enter the password, pin or pattern lock screen. Users have to do a long swipe with your finger either to repeat the gesture several times. A similar problem occurs when swiping notifications from the lock screen or while attempting to commit or reset the incoming call.
Google already know about the problem and do a fix.