I have been using the Google Health app since I got my new Samsung A50 last year. I'm using it to track my walks and to make sure I exercise enough to help balance out my desk job.
Up to the last major Android upgrade, it's been doing its job pretty well. However, about the time the Android has been upgraded to a new major release, around Spring this year, it's started messing up the "active minutes" graph. Instead of the activity being recorded at the time it has occurred, it is recorded in the past or in the future, off by a few hours or even on a previous or next day. If I'm actually using the exercise function (like the Walk mode) it can even record the same activity twice, once as part of the exercise, and once at some different point in time, in the past or even the future, where it's not immediately displayed, but eventually shows up in a few hours.
The offset is not constant, it can be 1 hour or 10 hours, seemingly at random.
Probably related to that, the automatic exercise detection is getting confused and detecting a series of 15 minute bouts of exercise, even if it was a long uninterrupted walk. It wasn't like that before.
All of this is making the exercise records totally bogus.
I tried the suggested solution of stopping the app and clearing the cache/data, a few times it worked for a short while, sometimes it didn't work at all. Looks like the code that is counting the active minutes and populating the activity graph is not doing it correctly anymore. In any case, an important app from a major phone manufacturer should not require this sort of kludges to do its main job.
Also, a few times in the last months the step counter has stopped counting steps altogether until the phone was restarted. And this in the middle of a reasonably long walk. Maybe it's a different bug, or maybe it's related.
I thought it was due to adding the Health applet to the wallpaper, but I've removed it since and it still keeps happening.
I haven't tried Endomondo or other health apps, so I'm not sure if it's just Samsung Health or all those apps that are broken in the new Android.
Please let me know if there's anything I can do to help confirming and understanding the bug.
More detail: in the exercise history, "Walking" is recorded with correct start time and duration, but "Walking (auto)" is recorded with random time offset.