If like me when recording an activity on Strava and it stops recording a little way into your ride then I have a solution:
Open the Phone Manager App which is pre-installed on the phone. Go onto Power Saving and select the Normal Power Plan, additionally add 'Strava' to your Protected Apps. This should prevent your phone from closing down Strava whilst it's recording.
Hopefully this will have been some help to a very select audience somewhere out there!