Yes - everyone blames everyone else! I have got Strava to sync cycling data with Health occasionally but it is never stable for long. Usually it shows 'no data' but sometimes it shows data from many weeks back but not recent data, sometimes only today's entry etc. (the original doubling problem seems solved). You can reset by:-
- restarting the phone (which forces Health to reset)
- deleting Strava, including the data in Health when requested and reinstalling (App store/purchased/not on this phone), then relogging in to Strava
- note that Strava should be linked again to Health and include at least cycling plus 'workouts' (this matters).
- if Health still cannot see Strava data (which should go back many weeks) try restarting the phone again.
Any of this might work but does not always - but if you keep fiddling it will eventually work, only to die again soon, probably when you add another ride. I suspect the core problem has to do with timing/clocks as between Strava and Health, based on some odd values sometimes, but I am not really sure. Since Health defaults to 'No Data' whenever it has problems it is hard to know. I suspect Apple is more guilty than Strava but again hard to be sure...