Visual Voicemail (VVM) is not properly customizing vibration notifications. Users will get the visual and audible notification, but no vibration.
Precondition: Go to settings > General > Apps & Notifications > Notifications > Apps > Advanced settings
Open voicemail and set up notification sound and select "sound with vibration" option
The device should get correct notification sound and should vibrate.
Receive voicemail and observe no vibration.
Please do not hard reset or exchange handsets for this behavior.
This will be addressed in a future Software Enhancement.