Help with Map to KML tool - creating a composite image

[LindsayRaabe_FPCWA]

I'm trying to use the Map to KML tool (new in 2.7) and not having much luck. I've successfully managed to export a map to KML when the export settings are to maintain layers, but when I try and run the same tool but to output a "Single Composite Image", it ignores the "Extent to Export" settings and gives me something quite **bleep**. See screenshots below of the map view, tool parameters used, and the result. 

As you can see, not the image I was expecting (which is focused on the green blob). The tool looks quite straight forward. Input, output, layered or image, extent, image properties. What am I doing wrong?