If heart rate is unavailable for some time, Strava just averages the missing part making the total average useless.
e.g. Watch fails to record heart rate of the first 5 minutes of a 30m run. Strava then records a 5 minute interval with (very) low heart rate. Then at the end if the run the total average is lowered significantly by that stretch.
i would like these null readings be ignored or at least have the ability to choose how they are handled/extrapolated (max/avg/last value/first value/ignore).