Media Error message problem

I have noticed that when I carry my iPhone with me while walking or running, if my Forerunner 945 is tracking my activity, I frequently get a Media Error message and my watch goes back to the normal watch face. This really messes up the stats when I go back to tracking by pressing the Start button. I regularly refresh my watch by turning it off, but this does not help. Other than not carrying my phone, is there a fix for this problem. I called Garmin tech and did some troubleshooting, but this didn’t solve the problem.