HomePort won't recognise mapset .img created by MapSouce

From Mapsource I am able to save map sets into an SD card for my GPSMap76CSx and they always work fine in the GPS.

If I plug the SD card into my Laptop and start HomePort, the card is detected however HomePort will not recognise the .img files at all.

This is consistent across map products and different mapsets, no .img is detected. They can be seen OK in windows.

HomePort is 2.03, Mapsource is 6.16.2