Sense running distance/ pace keeps changing using GPS

[kow]

I have been using Fitbit Sense for the last 2 months (and was using Fitbit Ionic before that) and pretty much running the same route for the longest time. Distance (and hence pace) calculated by Sense has been off by 0.15 to 0.25 miles on a 4 mile route with each day, the reading being different. I understand there being minor differences but this seems very high especially for a $300 product! 

Moderator edit: subject for clarity 

[t.parker]

Set the stride length manually. If you use automatic stride length calculation, one run with bad GPS readings may badly affect stride length used during next run (distance of run is calculated with stride length and stride length depends on GPS).