Date Format in Power Bi

Hi Bush 

You don't do this type of formatting the way you are trying to do it.  

I also think you are misunderstanding the idea of display format and the way actual underlying data is shown to you on screen by PBI.

For example, with this data in my table

Once loaded into PBI, I can select that column and in the Format area, type in dd/mm/yyyy and I get this shown in a table visual

You don't need to use the FORMAT function to simply display data in a particular format.  

Using a format string as I've done here, the underlying data is not changed - you can see in the image above that the Data type still says it is Date/time.

Download this PBIX file to see my example

Maybe this article on custom formats will help 

Custom Formatting Strings in Power BI

regards

Phil