When configuring the x-axis in line charts, the initial start and end dates and times of the Fixed range option are quite random and usually outside the range of the data source.
1. Where does Tableau get these dates/times
2. Is it possible to set the initially displayed time to a default value, like 12:00:00 AM?
I work exclusively with Excel data sources with either month or week time granularity.
I believe Tableau uses a 3 month grace period on either side of the dates so that the entire view is centered in the range. You can manually type in 12:00:00 AM in the fixed Start date time.
Hope this helps a bit!