After our further investigation, we found that we actually get the UTC time from the database and timeAxis.timeZone actually work on both data and current date time correctly but the browser caching issue in our code causes the update on timeAxis.timeZone is failed and this lead to different time zone issue between data and current date time. This is our own issue and we already fix it. Sorry for inconvenience.
For the second issue, we call the replaceData() function to update the chart data. You're right. We do not define the dataLimitFrom and dataLimitTo. We will try to define them and see whether this problem can be solved or not.
Then, can zoomcharts give some notification when empty data set is pass in (especially for time chart)? In our project, we have a filter feature to manage the input data set. For example, the output value for last one hour. This chart will update continuously and the latest one hour data will be presented on the chart.However, we may observed that at certain time there is no input as this will lead to an empty data set. In our project, the chart state (for eg. drill down, zoom in, viewed time range) is saved and every data update, the chart will not return to the top level or the state like the new chart is plotted. When we already zoom in to very small unit time step, this is difficult to notice that whether the chart is empty or not without interact on it.