I was following a course on my Forerunner 965 and was also listening to audio on my headphones. Navigation alerts took over the audio and then audio resumed just fine for the "turn <direction> in <distance>" and for the "next, turn <direction> in <longer distance>". But the alert to "turn <direction>" got stuck in a loop where all it could get out was "tur-" followed by a sub-second clip of my audio, "tur-", audio, "tur-", audio. I couldn't get it to pause on my headphones. I tried turning them off and back on and it restarted. I was finally able to pause audio via my phone's screen and it spit out the full "turn <direction>" and was able to resume audio after that. But at the next turn the same thing happened. I was able to avoid it by manually pausing before the "turn <direction>" alert.
I'm assuming this is a Connect bug since my headphones were connected only to my phone. I know there's a report in the 965 forum to remove the navigation audio alerts altogether. For now, I've turned them off from Connect via More... -> Garmin Devices -> Forerunner 965 -> Navigation -> Alerts -> Turn Prompts (off). I haven't tested whether that turns off the beep/vibrate alerts on my 965 or not.