Sometimes (or maybe always?), when I switch from one timezone to another in my user profile, the timestamps in x-axis of the charts do not adjust properly even though the timestamp in the popup does adjust properly.
In the attached example, you can see that the timestamp in the x-axis is 03:09 and the timestamp in the popup is 12:09. I had just switched from UTC-5 to UTC+4 in my user profile, so that explains the 9 hour difference. The x-axis timestamps seem to be "stuck" in the UTC-5 timezone.