My Lily2 is significantly inaccurate when measuring walking distances. When walking 20 kilometers or more, it deviates by over 2 kilometers. I compare the distance with two other Garmin watches and with the distances displayed on the map. Connected GPS is on, and I carry my phone with me. I have already tried using a personalized step length for more accuracy, but this also doesn't seem te help. I have had two different phones since I got the Lily, but that makes no difference either. How can this be resolved?