A MSFT Support case has just concluded after many weeks of effort and testing with the result, it can't be done. The MSFT Support Engineers for PowerBI tried very hard to make this work but it's simply not possible. It's very unfortunate that the POST method using basic authentication is not supported. As you consider whether to expend engineering resources to address this issue, please review the following Microsoft Support Case: TrackingID #2303140040007067 (worked by: hardiksoni and talakaraki). Our company offers a Cloud Native SaaS platform for data analytics but many of our customers use PowerBI and want to access their data from our platform using PowerBI...however, our API's require POST method and basic auth. So now their investment in PowerBI doesn't help them and they are limited to accessing their agency's data from our client. And while we provide API access, to give them choice, it does them no good if they are using PowerBI.
Thank you for your consideration.
