Phone keeps vibrating on call after silencing/muting with turning the device to the front side

OS: 4.2.0.21 (Verla)
HARDWARE: XA2
REGRESSION: YES

DESCRIPTION:

this was working with every previous version of the OS.
the action that i made the turn and wanted to silence is visible on the screen saying that the call is silenced, but i actually is not.

PRECONDITION:

activate setting in gestures to silence/mute incoming calls and alarms

STEPS TO REPRODUCE:

turn around phone to silence/mute incoming call

EXPECTED RESULT:

phone does not vibrate anymore

ACTUAL RESULT:

phone keeps vibrating