Unable to change DirectQuery SQL Database connection to SSAS Tabular

I am unable to replace an existing SQL Server Database data source with an SSAS Tabular one. It doesn't make sense to have to create a new file and a new connection to update the data source for a report, especially since you are unable to copy dashboard/pages from one file to another. Should be able to either replace connection within the same file, or enable copy/paste across Power BI files.