Unable to reject incoming call (waking up from sleep)
When receiving a call and waking up from deep sleep, the blue LED notification light starts blinking, the screen turns on, the mobile signal appears on the lockscreen and then the incoming call screen is shown and the phone rings. Pressing the call reject button on the screen does not work. The screen goes blank, then the incoming call screen shows again. Call reject still doesn't work.
Note that making another call when the phone is awake and screen locked does not show the blinking LED first, the phone starts ringing with the screen staying dark - pressing the on button shows the incoming call screen and the reject button works.
With the screen unlocked the incoming call screen pops up and the call can be rejected successfully.
I guess this is a minor issue as you usually answer an incoming call. You can also let it ring if you don't want to answer.