Open Windows 10 notification for outgoing calls shows last incoming phone number

Hello,
I'm having an issue with my setup. I've got Join running on my Surface Pro 4, and on my rooted Nexus 6P running 7.1.1 with various Pixel addons. When I receive a phone call I get a notification on my Surface displaying who is calling me, however when I make a phone call the resulting notification on my Surface just lists the last person who called me, not the person I'm calling.
I've looked everywhere I can in both the Android and Win10 apps for a checkbox that I'm missing but I can't find one.