Call waiting flashes for 1 second, then missed call

I have vvx-350 and the client it has one DID number on it. When I am on the phone, someone calls me from external number, I get a "flash" from the desktop client and it goes to VM.

I have call waiting set for 30 seconds. 

how many concurrent calls can a zoom DID take?

Cisco call manager you could allow each line take 4-6 inbound calls at once. 

Please don't tell me I have to make an executive line now a Call q?

Apply all the Q settings if there were 10 people getting calls just for 2 people to see inbound calls, put them on

hold, transfer them, join them to an audio conference, etc. 

powerpack add-on is enabled and still same result