Brand new Versa 4 exercise app will not work. I start the app when my run begins but it randomly turns off and I return to a black screen. I touch the button and then the Fitbit logo appears as though I am just turning it on. No exercise has been tracked. Sometimes it will track for a few mins. Other times 20 mins. But never the whole run. How can I fix this? Any ideas? Super disappointed as I bought it yo track my runs
