Exactly same problem here. I think the issue is there when we use in single sim mode only. Vibration happens in dual sim it seems. Must be a software bug, hoping for an update soon.
Hi... Regarding vibrate when answered issue, if we enable touch vibration option in sound settings menu, then the vibration when answered option works for all the answered call in both the SIM card.
But, majority don't like to enable touch vibration and other system vibration option.
So, I feel that it should be a independent function.
My phone vibrates on answered calls regardless if I have touch vibration enabled or not