[Therion] KML from Therion no longer working in Google Earth?

I don't know why, but kml files for my surveys produced by Therion appear to have stopped working in Google Earth. Any therion kml file I try (including ones which worked in the past) now just show a point in central Africa with the whole continent visible at the zoom level. If I zoom to where the cave survey should appear then I see nothing there. I have attached a very truncated sample kml file (I deleted most of the points from the polygon to keep it simple. Footleg