We have been receiving a lot of crash reports from Running Mate users after v3.7 release. We’ve found the issue and working on the fix. Next release v3.8 will fix some of the issues but not all of them since it was submitted a week ago.
Most of the issues are related to Live Tiles so we are rolling back to old style Live Style in v3.8. Adding accent coloured tiles use a lot of memory and result in crashes on low memory devices. In the mean time, you can disable updating live tile in the app or from the phone settings. Also, make sure you backup your runs frequently. Thanks for your patience.