Progress bar doesn't work when sending maps to Edge 1050

When mounting the Edge 1050 on a Windows PC, it doesn't show up as a drive letter, as the previous Edge units did, but shows in Windows Explorer as "Edge 1050". When sending maps to the 1050 with Basecamp, the progress bar doesn't show anything while the map is being sent - it just says "Initializing", with the progress bar filled with diagonal blue and white stripes, and remains unchanged while the map is being sent. The maps do actually get sent OK, but no indication of progress until the send is complete. This is with Basecamp 4.7.5.