Navigation doesn't start with Siri Eyes Free
I'm using iOS 8.3 (iPhone 6) with a 2016 Acura ILX. Bluetooth connection and Siri Eyes Free generally works fine. However, if I use Siri Eyes Free to ask for navigation, like "Take me home", although Siri responds with "Getting directions to home", the turn-by-turn directions never begin. If I unlock my phone and open the Maps app, the navigation will begin (and play through the car speaker as it should), but it's not very convenient to take my phone out of my pocket to get things started.
Am I doing something wrong? Is it normal behavior to not start navigation until the phone is unlocked? Is there a setting that I've missed?
iPhone 6, iOS 8.3, null