Sql.Database Query argument removed from production dataflow overnight

I have production dataflows running successfully for months that began failing last night. On investigation, I discovered the Query argument had been removed from the Sql.Database function like this

qs = "select * from table",
Source = Sql.Database(server, db_Reporting, [Query=qs, CreateNavigationProperties=false])

magically transformed itself to this

qs = "select * from table",
Source = Sql.Database(server, db_Reporting, [CreateNavigationProperties=false])

When I edit the line to re-add the Query argument, Power BI disappears it again.

I started a new dataflow to see if I could do it in a completely new dataflow, and I noticed for the first time the Advanced option for native queries. HRMMMMM. Don't know when that rolled out because I haven't added or edited dataflows in over a month, but clearly something with this functionality is causing problems. I added a new dataflow using the new native query experience, and it created code like this

Source = Sql.Database(server, db_Reporting, [Query="select * from table", CreateNavigationProperties=false])

I tried editing that back to have a separate query string, and it disappeared the query argument again.

Did I miss an announcement that dataflows would be forced transfromed like this? 

Does the Query argument no longer support references?