Multiple error generation when using geojson as a reference layer in Azure Maps

FYI the root cause of the problem is that some of the "features" (ie. map regions) in my GeoJSON file had "geometry":null - meaning that they were regions that should not be drawn. While most mapping software can handle this problem, Azure Maps reference layers cannot.

If you find yourself with this problem, you will need to delete any features in your GeoJSON file with the "geometry":null tag (see example below). The Power BI devs have told me that they expect a fix to be shipped in a couple of months (but no promises)