Sip Dialer Interferes With Answering Call

I set up the built in SIP Dialer so I could make outgoing calls from my 6P using my home office VOIP line. I've noticed that when the SIP dialer is active (but not set to answer calls) if a call comes in when the screen is off incoming calls crash hangouts and I can't answer the call. If I turn off the SIP dialer (just for outgoing) everything works fine.

Any thoughts on how I can correct this? The SIP dialer is very convenient for me to make outgoing work calls when I'm not at my desk.