Trouble using img maps in Basecamp 4.7.4

It used to work with previous versions.  I can no longer make it work.  I'm putting the img files in AppData>Garmin>Maps> as instructed.  The maps I'm trying to use are from Open Topo Maps.  I've used Open Street Maps before in the past with no issues. What gives? 

  • BaseCamp never has read .img files like that. You need either a physical or virtual removable drive with the .img files in a folder named Garmin

    Some OSM maps come with an installer allowing them to be installed to a c drive for BaseCamp to read, that would have been how you did it previously.