Product: Vivomove Style
I've had my watch for about a year and a half. I use it primarily to track running activities with GPS turned on.
For roughly the last two months, I've noticed the measured distance becoming wildly inaccurate. I've had ~5 mile runs be measured as ~8 miles and ~10 mile runs be measured as ~17 miles. The 1-mile "lap" notifications on the watch usually start off looking normal during the run before they grow more (incorrectly) frequent as it goes on.
I often run with the Runkeeper app active as well (as it provides helpful audio cues) and the GPS measurements there are accurate to self-measurements on Google maps.
Any guidance would be appreciated!