Post a link to the activity. Are you editing the activity in the GC app on android?
If you want to fix your activities, Export Original, delete and reimport. And, of course, do not edit in Android!
By the way, take a look at the word "Summary Data: Edited" just above you Gear on the lower right of an activity in GC web - it indicates the problem. It got edited even tough you didn't touch it.