DirectQuery with Oracle Datasource fails

Running Power BI Report Server version Version 1.4.6969.7395 (January 2019)

Using the 12.2.0.1 Oracle 64-bit drivers.

Creating a very simple report in PowerBI desktop Version: 2.65.5313.1562 64-bit (januari 2019) using DirectQuery against an oracle database. The Report works from PBI Desktop, but when uploaded to the Report Server it fails with a "Unable to access the the Analysis Services" message.

Creating the same report as an imported report works fine on the PBI Report server, even when doing a scheduled refresh.

In both cases using basic authentication.

I notice that the datasources under the Manage/Datasources info in Report server look different in the two cases:

For DirectQuery:  "datasource=myserver.company.com; persist security info = True"

For Imported: "myserver.company.com"

However since they cant be changed I dont know if this matters.

Any suggestions on how to get this to work?