Question [Q] No notification sounds while playing music?

Hey guys,

Just got my M8 last week and I love it, but there's one thing so far that has been bugging me. When either playing or streaming music via BT in the car or via headphones at the gym/home, I've noticed that my notification sounds will not come through. Every other android phone (or iphone) that I've owned that I can remember has always attenuated the music for a second to play the notification sound. So far, I have not been able to figure out how to get my M8 to do this. It doesn't even vibrate to let me know I have a text/email/whatever... at best, I'll look down at the phone and the notification light will be blinking.

So, can anyone point me in the right direction to get this feature working again?

Also, FYI - I'm on the T-Mobile stock, rooted ROM with Xposed installed and s-off