I have a fully qualified date table to which I have added a column that contains a decimal number representing the year fraction. The Excel formula takes an existing "DayOfYear" column and divides by 365. After calculating the results in this manner, I then copied the column and pasted the results as "Values," so in my spreadsheet I have a perfectly normal column of decimal numbers.
When I import this column into the existing date table in Power BI, however, this new column is populated with "null" instead of the data that appear in the spreadsheet.
I switched the data type around and tried everything including text. Nada. I finally deleted the column in the Excel spreadsheet and added a calculated column to the spreadsheet in the PBI Query Editor, which is working.