I made it work by copying the SD card to a Flash/jump drive and using that on the computer w/Homeport
I like SUSSAMBs idea.
imdisk 2.0.10 which is an older version here at 576kb https://www.majorgeeks.com/files/details/imdisk_virtual_disk_driver.html
works for creating a virtual and removable drive, and homeport and garmin express can see it.
Once installed open the 'Imdisk virtual disk driver - go file mount new disk
For image file - navigate to a folder somewhere on your pc that this file will live. it will say the file does not exist and you say yes to create it.
set a drive letter.
set a size in megabytes or gigabytes
tick virtual disk drive access image file directly and tick removable media. ok
A few seconds later you will be prompted to format the new drive. I suggest FAT and give it a name like virutalSD
Once you have created a virtual drive and formatted. You can copy the files from SD cards to easily in explorer from then on.