Make automatic Date Table in Power Pivot work with Calculated columns
Currently, if I only have a date column in my model that comes from a calculated column I am not able to create an automatic date table. For that feature to work, I need a date column in my source file. Please remove this restriction.
Kenneth Barber commented
Instead of importing your data directly into Power Pivot and then adding a calculated column, import your data into Power Query (Get & Transform) and add your new column there. You can even exclude columns if you want. Then load the Power Query table to the Data Model.
To keep things organized, it is usually a good idea to restrict the Date Table to contain date-related columns only (date, year, quarter, month, month number, day, etc.) and then use a relationship to link it to your data tables. I doubt that the table that you are importing into Power Pivot contains only date-related columns.