Porkchop Porkchop, I also have a P6pro and had the exact same issue. After contacting my carrier, Verizon, they confirmed my device and reset my voicemail account. Resetting the account did not erase my greeting message or pin. Voicemail notifications resumed immediately. They even help me with testing. They called me back, left a voicemail, I got the notification right away and when I deleted the message, the notification turned off.
Hope this helps.