On further investigation, it appears there is a tiny dot in the Minimap, but due to the size of the game screen (1024x768), the size of the Minimap in the bottom left corner of the screen, and the large size of the whole level, the dot is almost invisible.
I've sort of cracked it by adding an invisible icon behind the player position, and drawing it as terrain.
I did intend to zoom the layer with the Minimap on, so that I could zoom in to a better looking Minimap, but there appears to be a bug with the Minimap on a zoomed layer.
It doesn't render as it should when the layer is zoomed at 200%, but at 100%, the Minimap now works perfectly.
Do the Devs consider this a bug with the Minimap, or just that it's being used outside it's intended scope of use?
Of course, a Zoom function built-in to the Minimap would remove the necessity to zoom the layer.