A Microsoft online analytical data engine used in decision support and business analytics, providing the analytical data for business reports and client applications such as Power BI, Excel, Reporting Services reports, and other data visualization tools.
In Visual Studio you're always working against an SSAS instance, and changing the source query doesn't automatically cause the SSAS to reload or "process" the data in the query. PowerBI Desktop always does these two steps together, but in Visual Studio they are seperate and you must reprocess the table to see the new column populated.