I've read previous threads about this issue and the suspicion that a previous activity wasn't stopped and saved, but that absolutely isn't my case because I was doing activities for three days straight now. The numerical data is correct, but the charts are flatlined. In the Desktop connect, I was able to zoom in towards the end and find varying data lines, but they don't line up with the amount of activity time I actually had. I definitely am not sure if trimming here is the best option.
Has anyone been able to figure out why this happens? Like I said: I definitely didn't not stop an activity and I've been doing activities daily and have all of the saved with no issues.