I did a search and couldn't find anything on this. So it is probably me.:o
The times shown on the horizontal axis of graphs are not the correct time. For instance on the "All Day Heart Rate" graph the latest time shown is 9:38 AM, but the current time is 3:40 PM. Or the sleep graph shows me getting up at 3:37 PM when I got up at 7 something AM.
I have checked the timezone and it is correct. My VivoSmart HR shows the correct time, as to my computer and phone. I am using Windows 10 and the Edge browser when this happens.