whatsapp calls still vibrating when do not disturb enabled.

[AC Question]

i can't say when it started, but before when do not disturb was enabled nothing apart from my alarm would sound, but now when someone calls with whatsapp it vibrates there is now sound but it still vibrates. regardless if i have it set to No exceptions or alarms only or custom anyone know why
running android 6.0.1
note 4
thanks