Turns out the Strava Android app is total balls for running. Bought a Garmin Vivoactive 3 today, went on what I thought was a much longer run. Tracking shows a much smoother route but only up to 2.5 miles from 2.4 (4k from 3.9). All the hinting around for a GPS signal was way over egging the distance.
Feels almost like starting from scratch. At least now I have a more accurate baseline.
Yep, I've experienced exactly the same thing. I had previously wondered what had happened to my good running speed. I was sick in January, and then after that seemed to have slowed down considerably. I put it down to recovery after illness, but after further reflection / investigation realised ALL my mobile phone recorded times were off because of the GPS adding about 10% extra on to the distance.