I cut a 1 minute section from a log file from 2/18/15 and uploaded it. The log was rendered properly but the date both on mouse over and on the axis was for 2/17/15. I checked the timezone and it was correct. Can someone tell me what I may have overlooked during configuration or if this is a real bug?
can you please ask in the forums and also attach a sample log file?
note that this is related to the website timezone set in piwik, check it's correct.