Direct Query - add tables after initial setup

I understand that Direct Query does not have capability to have more than one data source.  In fact, I suspect that's why this short-coming has not been found because probably almost no-one can use direct query (based on reading some topics in this forum if you "hold your face wrong" direct query won't work).

I was using the Sandbox database and then I switched to the Production database--I did not add the Production database as an additional datasource.

Once again, full steps to get where I am:

1) connected to datasource "Sandbox" and added 4 tables

2) did some testing

3) switched to datasource "Production"

4) everything still worked with 4 tables

5) tried to add additional tables

6) followed steps recommended above

7) add table dialog had *NO* tables selected

I get that *this* is not a big deal, but imaging having 40 tables out of 70 selected and just wanting to add 1 more.

Here's the background of why this needs to work correctly.  I'm explaining this because I have found that often people don't understand why I'm asking a question but once they understand my business and usability case for doing this a light bulb comes on for them:

I am really beginning to suspect that Direct Query is just not viable (it just has way too many limitations) and I need to see if duplicated most of the data into Power BI over and over and over is viable.  This eliminates most of the value of Power BI for one of the projects I'm targeting.

Having some unknown code performing some black box extract once a day is what my client already has with an extract for Tableau that kills the system for 8 hours every night so they can run reports on day-old data the next day.

The thought of having to add every dimension table back when I decided to add a signle additional fact tables is just not something I want to sign up for.

I see a lot of other usability issue with Power BI desktop too.  The developers would hate me if I was the product owner.  Things like the dropdown for the recent datasources not showing you the full name of the datasource (even when hovering over them)--try figuring out the right datasource when you're using a 70 character long AWS host name.