I ran into the wrong color (black) displaying on the solidgauge chart. I was changing the yAxis maximum and the chart measurement would render with the fill, rgba(NaN,NaN,NaN,NaN). I cannot post my code at the moment. I'll try a fiddle soon.
@nickdeamons Mine and Izothep's issues are about github - pre-release - version of the code. If your problem is visible with the current (or any published) version of Highcharts then this will probably be a different issue, so a demo is very crucial.