Q&A Filter for Today or Yesterday

I'm not sure I'm being understood.

I'm not questioning the ability to get data into PBI via REST.  I've accomplished that with Rui's PowerBI REST app.  I have data streaming into PBI every 10 seconds using the BasicFIFO option in the API via PowerShell.  Been running for 2 weeks.

Below.  To my original point, you CAN use dynamic features like "today" and "yesterday" in QA off this dataset - see pic.  It works.  If I replace "YESTERDAY" with "TODAY" in the Q&A line - magically, all my data filters for 7/14 instead of 7/13.  It's like a magic hidden feature that you can't choose in the filter UI, (though you even get a filter (see blue lines) on the nav oddly.)

The issue is that AFTER you've created this visual just as I've typed it and click "Pin" - there seems to be a bug in the dashboard, because over the course of a day or so it forgets to apply the timestamp filter that it was able to create in the first place.

So, is this a hidden feature of the Q&A experience - that perhaps only works on non-PowerPivot data?  If so, why is it hidden?  Why not a filter option that one can choose without having to type "for today"?

-Eric.