Mark,
MapRun6 uses the latest versions of geo-location software libraries and addresses some requirements Google have introduced about background tracking.
We've not had other reports of issues... and MapRun6 has made tracking more reliable even on problematic phone brands/models.
Having said that, all Android manufacturers like to try to extend battery life by restricting Apps from running in the background. The general advice for handling this is:
http://maprunners.weebly.com/phone-settings.htmlIn particular for a Google Pixel, this recommends checking: Settings > Apps > MapRun6 > Advanced > Battery > Background restrictions.
Let us know if you still have problems.
Peter